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Bizarreness of size and shape in dream images
Consciousness and Cognition Consciousness and Cognition 16 (2007) 381–390 www.elsevier.com/locate/concog
Bizarreness of size and shape in dream images P.C. Cicogna *, M. Occhionero, V. Natale, M.J. Esposito Department of Psychology, University of Bologna, Viale Berti Pichat 5, 40127 Bologna, Italy Received 19 October 2005 Available online 25 July 2006
Abstract Bizarreness in dreams is defined as an unusual combination of features in the phenomenal unified consciousness, that is, an incoherent simulation of the waking world. The present study investigated the specific mechanisms underlying dream image production and the phenomenal unity of consciousness by focusing on size and shape bizarreness. Data were derived from a Dream Data Bank of experimental dream studies. Analyses revealed that feature distortion was quite infrequent. Results are discussed in terms of cognitive processes proposed in a dream production model. Theoretical cognitive constructs, such as Kosslyn’s imagery model, memory systems functioning, and binding, were used to speculate about these two specific types of bizarreness. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Dreaming; Binding; Size bizarreness; Shape bizarreness; Consciousness; Imagery; Memory
1. Introduction Oneiric bizarreness has been the subject of many classifications in the experimental literature on sleep and dreaming, and has been explained in terms either of ‘‘cognitive error’’ or as an active censorship mechanism. The accounts vary in function of a given study’s perspective, which can be cognitive (e.g., Cicogna & Bosinelli, 2001; Foulkes, 1985; Reinsel, Antrobus, & Wollman, 1992; Revonsuo & Tarkko, 2002), neurophysiological (e.g., Hobson, 1988; Kahn, Pace-Schott, & Hobson, 1997; Seligman & Yellen, 1987), or psychoanalytical (in particular, Freud, 1900). Cognitive studies on oneiric bizarreness have focused on accounting for violations of real-world rules, such as violations that result from either a low degree of engagement in associative and control processes for numerous and disconnected mnemonic inputs (Cavallero, Cicogna, Natale, Occhionero, & Zito, 1992; Cicogna & Bosinelli, 2001; Cicogna, Cavallero, & Bosinelli, 1991) or from a lack of guidance from external stimulation (high thresholds) and from the Self system (Foulkes, 1985, 1999; Reinsel et al., 1992). Despite their differences, however, cognitive approaches do not consider bizarreness an invariant and dominant property of dreams, and dreams are thought to be reasonably coherent and not bizarre at all. *
Corresponding author. Fax: +39 051 243086. E-mail address: [email protected] (P.C. Cicogna).
1053-8100/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.concog.2006.06.006
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Hobson et al.’s (1988, 1995, 2000) neurophysiological perspective differs in various ways from the cognitive perspective. Dream bizarreness is attributed to the casualness of mnemonic input, which is due to the neurophysiological characteristics of sleep stages (specifically REM sleep), where advanced cognitive processes are unable to adequately organize a scene simulating the real, waking world. The substantial difference between the two lies in the view of bizarreness as an essential and constant characteristic of oneiric activity: Dreams are pervasively bizarre.1 Both approaches, however, consider bizarreness as being independent of intrinsic motivational and affective significance, which is, conversely considered fundamental in psychoanalytical theories, and as merely the product of an impairment in cognitive system engagement, due to a specific psychophysiological condition. Yet, all authors referring to cognitive processes provide a global account for bizarreness, as if the broad range of violations, compared with the waking world, are uniformly explicable, in terms of a general functional deficiency in cognitive processes during dream generation. Revonsuo and Tarkko (2002) maintain that bizarreness should be reconceptualized as an unusual combination of features in the binding of different information sources. The types of ‘‘errors’’ that appear in the oneiric scenario could be either the result of a malfunctioning in different and specific cognitive processes that are active during waking, or the product of a particular type of cognitive functioning that occurs during sleep. Specifically, if a dream is a multimodal hallucinatory simulation of the real world (Foulkes, 1985), oneiric distortions may pertain to all aspects of reality represented: images, combinations of environmental features, spatio-temporal organization, representation of Self, non-self character representation, physical and logical constraints, etc. . . Each one of these aspects could be explained on the basis of the various mechanisms that come into play in dream production and in the phenomenal dream experience. Revonsuo and Tarkko (2002) have previously raised this problem and proposed examining dream bizarreness in detail, starting with an exploration of the specificity of bizarreness in the representation of human characters in dreams (Kahn, Stickgold, Pace-Schott, & Hobson, 2000 analyzed the topic from a neurophysiological perspective). We agree with these authors concerning the need for more detailed studies of bizarreness, with the aim of learning more about the specific mechanisms that underlie dream production and the (coherent and/or incoherent) construction of phenomenal unified consciousness in dreams and wakefulness. Hence, it was this need that inspired the present study, which examined two specific types of bizarreness: size and shape phenomenal distortions in dream images. The empirical data available to date on the frequency of bizarreness in oneiric activity have shown a broad variability both within and across sleep stages (Natale & Esposito, 2001), especially in the most studied stages of REM and NREM-St.2. Specifically, data collected from different sleep stages have yielded estimates of bizarreness ranging from 33% to 43% in Sleep Onset (SO), from 47% to 79% in St.2; from 50% to 54% in Delta sleep (SWS), and from 60% to 90% in REM sleep (for a detailed review, see Colace, 2003). It is not possible, however, to extract the specific weight of shape and size distortions from these general quantitative data. In fact, from a mental processing perspective, bizarreness is explained as a whole, and is generally considered as ‘‘any events outside the conceivable expectations of waking life’’ (Domhoff, 2005). We based our study on an existing corpus of dream reports, collected over the past 30 years in our Sleep and Dream Laboratory, during different sleep stages and over the course of various experiments, which allowed us to selectively obtain reports with distortions of both size and shape. The reports are collected in the regularly updated Dream Data Bank (DDB) (Natale & Esposito, 2001; Zito, Cavallero, & Cicogna, 1990; Zito, Cicogna, & Cavallero, 1991). The first aim of the present study was to verify the quantitative incidence of size and shape bizarreness; the second aim was to describe the qualitative characteristics of these two types of bizarreness, and the third was to attempt to formulate interpretative hypotheses about the cognitive mechanisms that might be involved in the phenomena of size and shape bizarreness. We based our speculation on the current state of knowledge concerning waking cognition.
1
It is worth noting that the neurophysiological approach assigns a central role to REM processes for dreamlike mentation, whereas the cognitive approach assumes that dream production system is virtually the same across sleep stages.
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2. Method The DDB consists of two sections. In the first section (the Data Base), reports are coded based on three parameters: (a) information about the experiment, (b) electropolygraphic and physiologic information about the sleep stages during which dream reports were collected, and (c) information about the structure and content of the dream reports obtained by at least two independent judges. (Interrater reliability is usually higher than .80 for each dimension considered.) The second section of DDB stores the original dream reports, which are collected and identified by a progressive number code. All participants in the present study were paid university students, with ages ranging from 20 to 29 years. Experimental awakenings (only one per night) were carried out under standard electropolygraphic control (three EEG channels, two EOG channels, and one EMG channel). In Sleep Onset (SO), participants were awakened 5 min after the appearance of the first sleep spindles. Stage 2 (St.2) dream reports were collected after 10 min of continuous Stage 2 sleep, provided that at least 20 min had elapsed from the end of the preceding REM phase. Slow Wave Sleep dream reports were collected after 10 min of continuous delta sleep in either stage 3–4 or stage 4, but only when at least 30 min had elapsed from SO. REM-report participants were awakened 10 min after appearance of the first clear burst of rapid eye movements. On the whole, 827 dream reports (230 SO, 77 St.2, 129 SWS, and 391 REM) were sampled from the DDB for analysis. Only 391 (47.28%) (65 SO, 50 St.2, 72 SWS, 204 REM) reports with at least one bizarre aspect (presence/non-presence) were selected from the entire DDB corpus (see Table 1). These dream reports were then submitted to two independent judges who verified shape and size distortions. The following were judged to be shape distortions: (a) the presence of characteristics that do not typically pertain to a semantically represented character or object (e.g., suitcases with the shape of body parts, in the trunk of a car); (b) absence of characteristically distinguishing or defining parts of an object or character (e.g., a face lacking eyes); (c) fusions; (d) transformations/metamorphoses of objects/characters/animals into other elements, which may or may not belong to the same or other categories (e.g., a girl who becomes a small dog). Distortions were considered size distortions when the size of the object or character were non-realistic or were incoherent with respect to the other elements in a scene. Agreement percentage for Scale scoring was >85%. Judges corrected any scoring discrepancies, and the reconciled version was then used for data analysis. We also calculated the number of shape and size distortions present in each report and the relationship between the number of distortions and report length (density evaluation). Report length is codified in the DDB as number of Temporal Units (TU). A temporal unit is defined as whatever activities could synchronously occur and are not described as having occurred successively (Foulkes & Schmidt, 1983). We considered density of both size and shape distortions, given that several studies have shown a positive correlation between bizarreness and report length (Antrobus, 1983; Auld et al., 1968; Hunt et al., 1993; McCarley and Hoffman, 1981; Wood, Sebba, & Domino, 1989–1990). Table 1 Number of DDB reports with bizarreness, number and percentage of reports with size and shape bizarreness, number and percentage of size bizarreness, number and percentage of shape bizarreness SO
St.2
SWS
REM
Total
Significant comparisons
No. of dream reports
230
77
129
391
827
No. and percentage of dream reports with general bizarreness
65, 28.26%
50, 64.93%
72, 55.81%
204, 52.17%
391, 47.28%
SO < SWS (p < .0005), SO < REM (p < .0005), SO < St.2 (p < .00001), REM < St.2 (p < .05)
No. and percentage of dream reports with size and shape bizarreness
12, 18.46%
16, 30.00%
10, 13.89%
25, 12.95%
63, 16.11%
St.2 > REM (p < .001), St.2 > SWS (p < .05)
No. and percentage of dream reports with size bizarreness
9, 13.85%
11, 24.00%
8, 11.11%
22, 10.29%
50, 12.79%
No. and percentage of dream reports with shape bizarreness
9, 13.85%
8, 16.90%
4, 5.55%
12, 5.88%
33, 8.44%
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Qualitative analysis of bizarreness was conducted on report texts and on an interview that is routinely conducted in the sleep laboratory immediately following free recall, in order to clarify any unclear aspects of images or scenes described in the participants’ initial verbalizations. Statistical analyses were run with either Chi square or ANOVA, as required. Results were considered significant at p < .05. All tests were performed as non-repeated measures. 3. Results 3.1. Quantitative analysis As to frequency of bizarreness we examined bizarre dream reports from all sleep stages considered globally. Nevertheless, we also observed significantly different frequencies across sleep stages: SO presented fewer bizarre dream reports than REM sleep (v2 = 12.23, p < .0005), SWS (v2 = 13.99, p < .0005), and St.2 (v2 = 33.12, p < .00001). REM presented fewer bizarre dream reports than St.2 (v2 = 4.22, p < .05) did. Only 63 of the 391 bizarre dream reports examined (12 SO, 16 St.2, 10 SWS, 25 REM) yielded at least one size and/or shape distortion referring to characters, animals, or objects. Given that some reports contained more than one bizarre aspect, the total sample of bizarre features was 83: 50 size distortions and 33 shape distortions. Compared to both the entire sample (7.62%) and the sub-sample of bizarre reports (16.11%), the frequency of reports with shape and/or size distortions was low, independently of sleep stage. That is, nearly one sixth of the dreams judged to be bizarre contained at least one dimensional distortion. Yet, once sleep stage was accounted for, a higher percentage of dream reports with shape and/or size bizarreness was observed for St.2 (30.00%) than for either REM sleep (v2 = 11.57, p < .001) or SWS (v2 = 5.77, p < .05). Results concerning the density of size and shape bizarreness per sleep condition are shown in Fig. 1. Size bizarreness density (.40 ± .49) was significantly higher than shape bizarreness density (.20 ± .36) (t62 = 2.45; p < .05). Yet, once sleep stage conditions were considered, the difference was significant only for REM sleep (t24 = 2.40; p < .05): .45 ± .42 and .09 ± .06, respectively. Two one-way ANOVAs (sleep conditions: 4 levels) were then run separately for each dimensional distortion, and results showed that density of size distortions did not differ per sleep condition, whereas significant differences emerged for shape distortion (F3,59 = 3.92; p < .05). The post hoc analysis (Tukey for unequal samples) revealed that the density of shape distortions in SO was greater than in the REM condition (p < .05). Certain recurring modalities in the appearance of dimensional distortions during dreaming, were detected: As to size distortions, enlargement phenomena were observed in 83% of all examined cases, whereas the shrinking of single elements in relation to oneiric scene context were present in 17% of the reports considered. Fusions accounted for 54% of all shape anomalies noted, whereas metamorphoses accounted for 33%; both types of distortions were equally subdivided between intra-categorical and inter-categorical modifications. Given that the sample size did not allow for further statistical analyses, these data were used in the qualitative appraisal of the two distortion typologies. 1.2
mean density
1 0.8 size shape
0.6 0.4 0.2 0 SO
St2
SWS
REM
sleep stages Fig. 1. Mean density of size and shape bizarreness across sleep stages.
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3.2. Qualitative analysis 3.2.1. Size distortions In some instances a single element filled the entire visual screen with a badly defined, or even an empty background. Indeed, there was no reference system that might allow for estimations of size relative to other objects in the scene, but there was a type of ‘‘zoom effect’’ on a single percept. Ex. n. 1 ‘‘. . . then the size of the backpack, it seemed truly enormous to me, gigantic as if a whole person could fit into it... it was as if I was practically looking into the backpack, right inside the backpack, as if it was framed by another television camera that was entering into the backpack; the whole scene was completely filled with the image of this backpack into which I was looking. . .’’ Ex. n. 2 ‘‘. . . a personldots has a small reptile attached to their foot, it’s not really a reptile but a sort of crocodile, but tiny, however as time goes by, bit by bit, it becomes bigger and bigger until it becomes a normal crocodile. . ..’’ Ex. n. 3 ‘‘. . . I was in a hospital corridor, it was the department where I work as an intern, and I saw many white gowns, a lot of people who were walking, then, from the entrance an enormous person entered, really big—a gigantic person, who filled the whole doorway, I couldn’t fit him into the frame, I only saw outlines, margins. . .’’ In one instance, image enlargement was such to prevent the image from completely fitting into the visual field, and fragments of the entire image were presented as a series of frames. Ex. n. 4 ‘‘. . . in the stream there was a long snake: really, really, really long. . . it was so long! When I saw it, it was as if I was looking at a photo; as if I saw frames of the photo and then I see. . . in the first photo frame there was a head and part of the body, but no tail, all the rest of the snake was in the following frames. . .’’ In other instances, size distortion was noticeable despite the presence of a background in the scene and/or other objects that should serve as parameters for establishing correct relations among the various elements and their organization, in relation to the background. Ex. n. 5 ‘‘. . . there was a small basket, but I saw that a normal-sized horse passed through every now and then, after a while though, that same basket was full of cats, despite the fact that it was small, it was full, there were probably about 10 cats, I remember that there was the mother and all her litter. . .’’ (in the dream I was astonished and sad to see that there could be so many cats in such a small basket) Ex. n. 6 ‘‘I was in a lane, and I stopped to speak to a person who had an enormous head with a large disproportion between head and body; he was a very odd person; his head was as large as the shoulders, about one meter. . ..I was not surprised by the fact that he had such an enormous head, I was considering this as if it were a normal situation.’’ 3.2.2. Shape distortions The most common instances of shape bizarreness were fusions of perceptual characteristics belonging to various objects, characters, or animals within the same semantic category. In the following example the fusion occurs between the characteristics of different animals: a dog, a crustacean, and a feline: Ex. n. 7 ‘‘. . . it was an animal, like a dog, but it was more like a monster because it was kind of. . . it didn’t have any hair, it was as large as a dog, but it was as smooth as a shellfish, it was polished and hard. I don’t know . . .really large teeth and claws and. . .’’ In the following examples, the typical characteristics of two objects from the same category are combined into a more general type of bizarreness: Ex. n. 8 ‘‘. . . I was trying to put a cork stopper into a bottle, there’s a hammer in my hands, but as I wasn’t able to hammer it in, I was thinking of sharpening the cork with a tool. The bottle was a beer bottle, but it had the shape
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and the top of a champagne bottle, with the cork held in place with wire threads’’. (I found the bottle strange; not the fact that I wanted to hammer the glass.) Ex. n. 9 ‘‘. . . gigantic chair-lifts passed by, but they were different from normal chair-lifts as there were so many people inside. . .’’ (it had the shape of an enormous chair-lift, but it contained much more people: like a cableway)’’. In other instance, clear disassociations between the meaning of the object and its image were observed: Ex. n. 10 ‘‘my partner had a camera to take black and white photos, it was weird, it had the shape of a giant keyring, not of a camera’’ (it was identical to an old key-ring that I have in a drawer). Ex. n. 11 ‘‘Two friends and I had to put suitcases, packages, into the car. These packages that we loaded had the shape of human body organs’’. At times the fusion of characteristics belonging to several characters did not occur in a synchronized fashion but in a close temporal succession. The element that is responsible for the distortion in the following example is the accelerated activation of three faces attributed to a single character, who continued to maintain the same role and spatial location in the dream: Ex. 12 ‘‘. . . at the beginning, when he entered’’ (a reference to the boy with whom the participant dreams of arguing), ‘‘his face is interchangeable with that of two other people, it’s really always him, but represented by three different people . . . each face is replaced in sequence. . .’’ Metamorphoses were also noticed among shape distortions, i.e., unexpected transformations of objects/animals/characters into elements of the same of a different category. Ex. 13 ‘‘. . . I had previously massaged him with a strawberry cream that was similar in form to a book. . . the cream in the shape of a book was in a bookcase with many other books, which, however, once taken down from the bookcase could be used as creams. . . the books, while they were on the bookshelf were books, then once removed became creams. . .’’ Ex. 14 ‘‘. . . opposite my house there is a garden. . . so I look out the window and I see the girl who I used to go into the yard with when I was young. . . after looking for a while I realize that she notices me, and at this point she transforms into a dog and as soon as she notices me, she starts to wag her tail and she raises two of her legs in order to draw herself nearer to the window. . .’’ Ex. 15 ‘‘. . .I could see a room. . . I had a very narrow visual field, I saw a table in the center of the room. . .. but immediately I turned to face the center of the table and I saw a small doll on it, it was a person, probably a woman dressed like a doll, with the dimensions of a doll, who, as soon as she saw me, I mean, as soon as she noticed that I was watching her, she camouflaged herself, she was a brunette, she stiffened, trying to transform herself into a doll. . .’’. The generation of impossible shapes in the following example is the result of an attribution of anthropomorphous characteristics to objects: Ex. 16 ‘‘. . . of the merchant ships, there is one in particular and. . . from above the bridge of this ship there were colored eggs with small arms, and legs which dipped into the water. . . there were only these eggs that played like children taking a dip. . .’’. 4. Discussion Taking into account the low frequency of the size and shape distortions of dream images observed we cannot discuss the results in terms of sleep stages or cycles of sleep. So only speculative hypotheses on qualitative analyses will be advanced.
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4.1. Bizarreness as size distortion Size distortion refers to phenomena such as the enlargement or shrinking of single objects or characters, as compared to the relative dimensions of other contextual elements (e.g., a small basket, in which a normal-sized horse was occasionally able to fit, and ten cats, too). Representations of elements reported by participants as being of different dimensions than what they normally perceive during wakefulness are also considered size distortions (e.g., an enormous backpack in which an entire person could fit). From a cognitive perspective, imagery models (Kosslyn, 1983, 1994) could be used to qualitatively investigate oneiric size distortion. From a structural point of view, a mental image is made up of both a superficial representation yielding up phenomenal evidence to our experience and a deep representation containing analogical-propositional information (which is activated from long-term memory for representation of the mental image). Imagery theories have postulated the existence of a visual buffer with the functional characteristics of a perceptual tableau. It is thought that in this perceptual screen, size constraints must be consistent with the relationship among elements. We can reasonably suppose that dream generation also involves representation in the visual buffer of a number of objects and/or characters, whose dimensions must be continuously reset as the narrative advances. This process operates through image enlargement and shrinking, based on cues of depth, figure-background organization, and the relationship among elements that are simultaneously present in the scene. Images must be maintained through a process of visual rehearsal if these operations are to be possible in the absence of perceivable objects. In some circumstances, scarcity of contextual information serving as a background to organize the various elements could render size adjustment operations in a scene more difficult. This phenomenon would therefore create ‘‘zoom’’ or shrinkage effects, the perceptive rendering of which could give rise to an experienced phenomenon of size incongruence within the entire narrative sequence. In other situations, where contextual information is present, size bizarreness could result from a desynchronization in image and image-background rehearsal processes. The link among the images themselves, the images and background, and the sequence of the images throughout the visual narrative may produce a phenomenal experience that is bizarre. The visual buffer activity is a part of Working Memory activity—i.e., of a memory system that is less engaged during sleep than during wakefulness (Braun et al., 1997; Occhionero, 2004). This prevalent involvement of WM in the definition of image size might account for the quantitative differences that can be observed in size and shape distortions for all sleep stages. 4.2. Bizarreness as shape distortion Shape distortion refers to the presence of at least one anomalous element in the shape of an object or a character, i.e., fusions, the attribution of incoherent meaning, and the creation of unlikely objects. We also included metamorphoses—though perhaps not entirely legitimately—in our operative concept of shape bizarreness, i.e., when bizarreness involves sudden and inexplicable transformations of objects or persons through time. (We did not, however, consider unexpected changes of location.) One might account for shape distortions by referring to the involvement of mnemonic trace retrieval processes, which are activated from long-term memory systems for dream generation. As frequently reported in the memory literature, various verbal and visual types of information are encoded according to specific modalities in each particular subsystem: the (pre-semantic) Perceptual Representation System, Semantic memory, and Episodic memory. Memory systems during wakefulness normally operate in parallel integratedly (Schacter & Tulving, 1994). Yet, a dissociation between memory systems, or a desynchronization in the activation of memory systems, might occur during sleep, due to the particular psychophysiological condition in which the cognitive processes required happen to be functioning. Specifically, the proposal is that this phenomenon takes place between the Perceptual Representation System (where object shapes are encoded independently of meaning) and the Semantic or Episodic systems (where shape meanings are encoded). This phenomenon appears to be particularly frequent during Sleep Onset (when we observed a higher shape distortion density than we did for REM sleep). The nature of Sleep Onset images, which are frequently rapid sequences of hypnagogic hallucinations unrelated to a spatio-temporal context, could account for this event. Yet, we are also unable to explain why the density of Stage 2 feature distortions we observed were more
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frequent than they were in other sleep stages. This latter finding, however, is consistent with analogous data yielded by a previous study (Cicogna, Natale, Occhionero, & Bosinelli, 1998). 4.3. Bizarreness and phenomenal consciousness in dreams We agree with Revonsuo (Revonsuo, 1999; Revonsuo & Tarkko, 2002) that phenomenal consciousness in dreams and in wakefulness is due to the coherent binding of single elements. The concept of binding has gained ever greater attention over the last few years in Neuroscience (Kahn et al., 1997), in Cognitive Science (Treisman, 1996), and in Consciousness studies. In its broadest sense, binding refers to the ability of the mind and brain to produce coherent, integrated representations of the world, even though external/internal information is received in multiple forms (Revonsuo, 1999). From a cognitive perspective, it refers to the integration of input from distributed modular processing; and in consciousness studies, binding denotes the integration of phenomenal contents into a unified awareness. Hence, the unity of consciousness most probably depends on underlying neural and cognitive binding mechanisms. Awareness-related binding can be described as an ongoing mechanism, which is grounded on integrative (neural and cognitive) mechanisms operating at lower levels. Most likely, different types of binding act simultaneously to activate inhibition mechanisms. Thus, bizarreness may be considered an unusual integration of elements in combining images (or bits of information), as the filter represented by judgment and control mechanisms is usually ineffective during sleep. The present study was based on a model of dream generation in which phenomenal consciousness may be considered the product of the binding of information derived from continuous and iterative feedback between the bottom-up activation of mnemonic information from long-term memory (LTM) systems and the topdown activation of images and thoughts that are phenomenally present in the dream experience (see ‘dream generation model’ in Cicogna & Bosinelli, 2001). From this perspective, bizarreness could be generally described in terms of a poor functioning in executive processes (the working memory processes of inhibition and binding) that usually inhibit and combine single inputs yielded up to awareness from the circular process. It is in this sense that binding may be considered a process that gives rise to phenomenal consciousness. The assertion is inconsistent with a recent review of a working memory model in which Baddeley (2000, 2003) proposed the existence of a new component, an episodic buffer, which is thought to provide an interface between the central executive and long-term memory. This component is involved in binding operations, to form integrated episodes into a multi-dimensional code, and is assumed to be accessible to conscious awareness. 5. Conclusions Our study indicates a relatively low bizarre feature rate in dreams. Indeed, single dream images tend to be quite coherent with waking percepts, at least in terms of shape (only about 8% of the bizarre reports contained a shape distortion). These results are in agreement with findings from early experimental studies (Dorus, Dorus, & Rechtschaffen, 1971; Snyder, 1970), which yielded very low levels of bizarreness and further showed that the relatively infrequent bizarreness that occurs does so within the context of coherent dreaming. Information resulting from the simultaneous functioning of various long-term memory systems, and referring to the shape and meaning of dream elements, seems to nearly always overlap with images perceived during wakefulness. The hallucination of waking-like images seems to require less executive process engagement, particularly for binding, than the engagement required by continuous and coherent size updating. Although size distortions are relatively infrequent (only approximately 13% of bizarre reports), context-appropriate size representation seems to involve a high working memory load (visual buffer activity, rehearsal, binding), and therefore components that might be partially ineffective during sleep. As anticipated (see the previous section), an explanation for size alteration might be found in visual buffer capacity for containing images and visual buffer functioning. The oneiric scene unfolds through time: as the various elements filling up the visual screen are gradually activated, they require updating with respect to other images in the context. If rapid image updating does not occur throughout the entire sequence, the perceptive impression of an ill-proportioned object—or an object which requires a succession of images for its complete representation—can linger in the dreamer (see example n. 4). In this instance, it is temporal binding that is not
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working efficiently. In others, perhaps only a few elements—or even a single element on a badly defined or non-existent background—are activated. The absence of a reference background, which would allow the dreamer to estimate the relative size of objects, could provoke a ‘‘zoom effect,’’ such that a single element fills the entire visual screen (see examples n. 1–3). When the scene continues, rehearsal activity for the image maintains its size, and field adaptation processes are not activated. The same effect may occur when size distortion is noticeable, despite the presence of a background and/or other objects that should function as parameters for correct relations among the various elements. In these instances, a sort of erroneous attribution in the sizescaling of the image may be triggered. The image maintains the format in which it was first activated by the perceptual representation system (see example n. 5). Yet, example n. 6 (in which the head is out of proportion to the rest of the body) is more difficult to explain. Perhaps it was due to temporal displacement in image production, i.e., with the head being hallucinated first and the rest of the body afterwards. The body image was then ‘‘adapted’’ to the limited size of the mental screen, as if the head image were being rehearsed in the size of initial hallucination. In all these instances, the perceptual ‘‘error’’ appears to be linked to a lack in temporal integration of visual field elements. As to shape bizarreness, the attribution of an object/character to another object’s/character’s perceptual characteristics may be due to a dissociation between the activation of perceptual characteristics retrieved from the (pre-semantic) Perceptual Representation System and the activation of meaning retrieved from the (declarative) Semantic and/or Episodic memory systems (see examples n. 10 and 11). Conversely, fusions appear to be the result of the binding of various elements that are simultaneously available and which typically are associatively linked (or belong to the same conceptual category) (see examples n. 7–9), or are linked in specific, idiosyncratic ways known only to the dreamer. Other shape inconsistencies, which manifest themselves as rapid metamorphoses, might be due to a phasedifference or desynchronization of memory system activity (see examples n. 13–16). The assumption is one of an acceleration in the production of single images in the process of temporal binding. The images then follow one another with no coherent modification of other elements present in the scene. Moreover, the creation of impossible shapes is perhaps linked to original combinations of bits of information, which are only parts of meaningful shapes. Specifically, mnemonic activation that is not opportunely inhibited can trigger a process of binding, which produces a new shape (features binding). Our results suggest that size bizarreness can be effectively described and explained as the products of an impairment in the temporal binding of images. Although this inefficiency in coherent size integration (which is automatic during waking) occurs rarely, it is probably due to a desynchronization in image production processes. Yet, shape bizarreness, such as the bizarreness produced by feature binding seems to occur in response to two different and non-mutually exclusive phenomena: (a) when inputs are too numerous and associatively distant, given that they originate from a chaotic iterative feedback loop between bottom-up LTM systems activation and top-down dream image activation (Cicogna & Bosinelli, 2001); (b) when inputs lack a perceptive/ semantic link, due to a dissociation in the functioning of LTM systems. The case of metamorphoses, however, appears to be more complex from a processing perspective: the phenomenon most probably occurs when a large amount of input and/or when incoherent inputs are associated with a temporal binding problem. In conclusion, our dream production model proposes that the cognitive constructs of (integrated or dissociated) imagery and memory system activity (including LTM, WM, and binding mechanisms) could account for the specific types of bizarreness examined in the present study. Further investigations into the possibility of removing oneself, while dreaming, from the constraints of waking experience (i.e., the temporal and spatial laws of physics (gravity, speed, etc.), logic, story grammar, etc.) should guide future research, with the aim of better understanding mind functioning during various states of consciousness. References Antrobus, J. S. (1983). REM and NREM sleep reports: comparison of word counts by cognitive classes. Psychophysiology, 20, 562–568. Auld, F., Goldenberg, G. M., & Weiss, J. V. (1968). Measurement of primary-process thinking in dream report. Journal of Personality and Social Psychology, 8(4), 418–426.
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Baddeley, A. D. (2000). The episodic buffer: a new component of working memory? Trends in Cognitive Science, 4, 417–423. Baddeley, A. D. (2003). Working memory: looking back and looking forward. Nature Reviews. Neuroscience, 4, 829–839. Braun, A. R., Balkin, T. J., Wesesten, N. J., Carson, R. E., Varga, M., Baldwin, P., Selbie, S., Belenky, G., & Herscovitch, P. (1997). Regional cerebral blood flow throughout the sleep–wake cycle An H215O PET study. Brain, 120, 1173–1197. Cavallero, C., Cicogna, P., Natale, V., Occhionero, M., & Zito, A. (1992). SWS Dreaming. Sleep, 15(6), 562–566. Cicogna, P. C., & Bosinelli, M. (2001). Consciousness during dreams. Consciousness and Cognition, 10, 26–41. Cicogna, P., Cavallero, C., & Bosinelli, M. (1991). Cognitive aspects of mental activity during sleep. The American Journal of Psychology, 104(3), 413–425. Cicogna, P., Natale, V., Occhionero, M., & Bosinelli, M. (1998). A comparison of mental activity during sleep onset and morning awakening. Sleep, 21, 462–470. Colace, C. (2003). Dream bizarreness reconsidered. Sleep and Hypnosis, 5(3), 105–128. Domhoff, G. W. (2005). Refocusing the Neurocognitive approach to dreams: a critic of the Hobson vs Solms debate. Dreaming, 15, 3–20. Dorus, E., Dorus, W., & Rechtschaffen, A. (1971). The incidence of novelty in dreams. Archives of General Psychiatry, 25, 364–368. Foulkes, D., & Schmidt, C. (1983). Temporal sequences and unit composition in dream reports from different stages of sleep. Sleep, 6, 265–280. Foulkes, D. (1985). Dreaming: A cognitive-psychological analysis. Hillsdale, NY: Erlbaum. Foulkes, D. (1999). Children’s dreaming and development of consciousness. Cambridge, MA: Harvard University Press. Freud, S. (1900). Die Traumdeutung. Vien: Franz Deuticke. Hobson, J. A. (1988). The dreaming brain. New York: Basic Books. Hobson, J. A., & Stickgold, R. (1995). The conscious state paradigm: A neurocognitive approach to waking sleeping and dreaming. In M. S. Gazzaniga (Ed.), The cognitive neurosciences. Cambridge, MA: MIT Press. Hobson, J. A., Pace-Schott, E., & Stickgold, R. (2000). Dreaming and the brain: toward a cognitive neuroscience of conscious states. Behavior and Brain Sciences, 23(6), 793–842. Hunt, H. T., Ruzicki-Hunt, K., Pariak, D., & Belicki, K. (1993). The relationship between dream bizarreness and imagination: artefact or essence. Dreaming, 3, 179–199. Kahn, D., Pace-Schott, E. F., & Hobson, J. A. (1997). Consciousness in waking and dreaming: the roles of neuronal oscillation and neuromodulation in determining similarities and differences. Neuroscience, 78(1), 13–38. Kahn, D., Stickgold, R., Pace-Schott, E. F., & Hobson, J. A. (2000). Dreaming and waking consciousness: a character recognition study. Journal of Sleep Research, 9(4), 317–325. Kosslyn, S. M. (1983). Ghosts in the mind’s machine. New York: W.W. Norton. Kosslyn, S. M. (1994). Image and brain: The resolution of the imagery debate. London: MIT Press. McCarley, R. W., & Hoffman, E. (1981). REM sleep dreams and the activation-synthesis hypothesis. American Journal of Psychiatry, 138(7), 904–912. Natale, V., & Esposito, M. J. (2001). Bizarreness across the first four cycles of sleep. Sleep and Hypnosis, 3(1), 18–24. Occhionero, M. (2004). Mental processes and brain during dreams. Dreaming, 14(1), 54–64. Reinsel, R., Antrobus, J. S., & Wollman, M. (1992). Bizarreness in dreams and waking fantasy. In M. Bertini & J. S. Antrobus (Eds.), The neuropsychology of sleep and dreaming (pp. 157–183). Hillsdale: LEA. Revonsuo, A. (1999). Binding and the phenomenal unity of consciousness. Consciousness and Cognition, 8, 173–185. Revonsuo, A., & Tarkko, K. (2002). Binding in dreams. Journal of Consciousness Studies, 9(7), 3–24. Seligman, M. E. P., & Yellen, A. (1987). What is a dream? Behavioral Research Therapy, 1(25), 1–24. Schacter, D. L., & Tulving, E. (1994). Memory systems 1994. Cambridge, MA: MIT Press. Snyder, S. (1970). Phenomenology of dreaming. In L. Madow & L. Snow (Eds.), The psychodynamic implications of the physiological studies on dreams (pp. 124–151). Springfield, IL: Thomas. Treisman, A. (1996). The binding problem. Current Opinion in Neurobiology, 6, 171–178. Wood, J. M., Sebba, D., & Domino, G. (1989–1990). Do creative people have more bizarre dreams? A reconsideration. Imagination, Cognition and Personality, 9(1), 3–16. Zito, A., Cavallero, C., & Cicogna, P. C. (1990). A computer dream data bank. In Abstract book 10th Congress of the European Sleep Research Society, Strasburg, 206. Zito, A., Cicogna, P. C., & Cavallero, C. (1991). DDB: una banca dati per la ricerca sulla fenomenologia del sogno. Giornale Italiano di Psicologia, 5, 781–786.
Bizarreness of size and shape in dream images P.C. Cicogna *, M. Occhionero, V. Natale, M.J. Esposito Department of Psychology, University of Bologna, Viale Berti Pichat 5, 40127 Bologna, Italy Received 19 October 2005 Available online 25 July 2006
Abstract Bizarreness in dreams is defined as an unusual combination of features in the phenomenal unified consciousness, that is, an incoherent simulation of the waking world. The present study investigated the specific mechanisms underlying dream image production and the phenomenal unity of consciousness by focusing on size and shape bizarreness. Data were derived from a Dream Data Bank of experimental dream studies. Analyses revealed that feature distortion was quite infrequent. Results are discussed in terms of cognitive processes proposed in a dream production model. Theoretical cognitive constructs, such as Kosslyn’s imagery model, memory systems functioning, and binding, were used to speculate about these two specific types of bizarreness. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Dreaming; Binding; Size bizarreness; Shape bizarreness; Consciousness; Imagery; Memory
1. Introduction Oneiric bizarreness has been the subject of many classifications in the experimental literature on sleep and dreaming, and has been explained in terms either of ‘‘cognitive error’’ or as an active censorship mechanism. The accounts vary in function of a given study’s perspective, which can be cognitive (e.g., Cicogna & Bosinelli, 2001; Foulkes, 1985; Reinsel, Antrobus, & Wollman, 1992; Revonsuo & Tarkko, 2002), neurophysiological (e.g., Hobson, 1988; Kahn, Pace-Schott, & Hobson, 1997; Seligman & Yellen, 1987), or psychoanalytical (in particular, Freud, 1900). Cognitive studies on oneiric bizarreness have focused on accounting for violations of real-world rules, such as violations that result from either a low degree of engagement in associative and control processes for numerous and disconnected mnemonic inputs (Cavallero, Cicogna, Natale, Occhionero, & Zito, 1992; Cicogna & Bosinelli, 2001; Cicogna, Cavallero, & Bosinelli, 1991) or from a lack of guidance from external stimulation (high thresholds) and from the Self system (Foulkes, 1985, 1999; Reinsel et al., 1992). Despite their differences, however, cognitive approaches do not consider bizarreness an invariant and dominant property of dreams, and dreams are thought to be reasonably coherent and not bizarre at all. *
Corresponding author. Fax: +39 051 243086. E-mail address: [email protected] (P.C. Cicogna).
1053-8100/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.concog.2006.06.006
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Hobson et al.’s (1988, 1995, 2000) neurophysiological perspective differs in various ways from the cognitive perspective. Dream bizarreness is attributed to the casualness of mnemonic input, which is due to the neurophysiological characteristics of sleep stages (specifically REM sleep), where advanced cognitive processes are unable to adequately organize a scene simulating the real, waking world. The substantial difference between the two lies in the view of bizarreness as an essential and constant characteristic of oneiric activity: Dreams are pervasively bizarre.1 Both approaches, however, consider bizarreness as being independent of intrinsic motivational and affective significance, which is, conversely considered fundamental in psychoanalytical theories, and as merely the product of an impairment in cognitive system engagement, due to a specific psychophysiological condition. Yet, all authors referring to cognitive processes provide a global account for bizarreness, as if the broad range of violations, compared with the waking world, are uniformly explicable, in terms of a general functional deficiency in cognitive processes during dream generation. Revonsuo and Tarkko (2002) maintain that bizarreness should be reconceptualized as an unusual combination of features in the binding of different information sources. The types of ‘‘errors’’ that appear in the oneiric scenario could be either the result of a malfunctioning in different and specific cognitive processes that are active during waking, or the product of a particular type of cognitive functioning that occurs during sleep. Specifically, if a dream is a multimodal hallucinatory simulation of the real world (Foulkes, 1985), oneiric distortions may pertain to all aspects of reality represented: images, combinations of environmental features, spatio-temporal organization, representation of Self, non-self character representation, physical and logical constraints, etc. . . Each one of these aspects could be explained on the basis of the various mechanisms that come into play in dream production and in the phenomenal dream experience. Revonsuo and Tarkko (2002) have previously raised this problem and proposed examining dream bizarreness in detail, starting with an exploration of the specificity of bizarreness in the representation of human characters in dreams (Kahn, Stickgold, Pace-Schott, & Hobson, 2000 analyzed the topic from a neurophysiological perspective). We agree with these authors concerning the need for more detailed studies of bizarreness, with the aim of learning more about the specific mechanisms that underlie dream production and the (coherent and/or incoherent) construction of phenomenal unified consciousness in dreams and wakefulness. Hence, it was this need that inspired the present study, which examined two specific types of bizarreness: size and shape phenomenal distortions in dream images. The empirical data available to date on the frequency of bizarreness in oneiric activity have shown a broad variability both within and across sleep stages (Natale & Esposito, 2001), especially in the most studied stages of REM and NREM-St.2. Specifically, data collected from different sleep stages have yielded estimates of bizarreness ranging from 33% to 43% in Sleep Onset (SO), from 47% to 79% in St.2; from 50% to 54% in Delta sleep (SWS), and from 60% to 90% in REM sleep (for a detailed review, see Colace, 2003). It is not possible, however, to extract the specific weight of shape and size distortions from these general quantitative data. In fact, from a mental processing perspective, bizarreness is explained as a whole, and is generally considered as ‘‘any events outside the conceivable expectations of waking life’’ (Domhoff, 2005). We based our study on an existing corpus of dream reports, collected over the past 30 years in our Sleep and Dream Laboratory, during different sleep stages and over the course of various experiments, which allowed us to selectively obtain reports with distortions of both size and shape. The reports are collected in the regularly updated Dream Data Bank (DDB) (Natale & Esposito, 2001; Zito, Cavallero, & Cicogna, 1990; Zito, Cicogna, & Cavallero, 1991). The first aim of the present study was to verify the quantitative incidence of size and shape bizarreness; the second aim was to describe the qualitative characteristics of these two types of bizarreness, and the third was to attempt to formulate interpretative hypotheses about the cognitive mechanisms that might be involved in the phenomena of size and shape bizarreness. We based our speculation on the current state of knowledge concerning waking cognition.
1
It is worth noting that the neurophysiological approach assigns a central role to REM processes for dreamlike mentation, whereas the cognitive approach assumes that dream production system is virtually the same across sleep stages.
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2. Method The DDB consists of two sections. In the first section (the Data Base), reports are coded based on three parameters: (a) information about the experiment, (b) electropolygraphic and physiologic information about the sleep stages during which dream reports were collected, and (c) information about the structure and content of the dream reports obtained by at least two independent judges. (Interrater reliability is usually higher than .80 for each dimension considered.) The second section of DDB stores the original dream reports, which are collected and identified by a progressive number code. All participants in the present study were paid university students, with ages ranging from 20 to 29 years. Experimental awakenings (only one per night) were carried out under standard electropolygraphic control (three EEG channels, two EOG channels, and one EMG channel). In Sleep Onset (SO), participants were awakened 5 min after the appearance of the first sleep spindles. Stage 2 (St.2) dream reports were collected after 10 min of continuous Stage 2 sleep, provided that at least 20 min had elapsed from the end of the preceding REM phase. Slow Wave Sleep dream reports were collected after 10 min of continuous delta sleep in either stage 3–4 or stage 4, but only when at least 30 min had elapsed from SO. REM-report participants were awakened 10 min after appearance of the first clear burst of rapid eye movements. On the whole, 827 dream reports (230 SO, 77 St.2, 129 SWS, and 391 REM) were sampled from the DDB for analysis. Only 391 (47.28%) (65 SO, 50 St.2, 72 SWS, 204 REM) reports with at least one bizarre aspect (presence/non-presence) were selected from the entire DDB corpus (see Table 1). These dream reports were then submitted to two independent judges who verified shape and size distortions. The following were judged to be shape distortions: (a) the presence of characteristics that do not typically pertain to a semantically represented character or object (e.g., suitcases with the shape of body parts, in the trunk of a car); (b) absence of characteristically distinguishing or defining parts of an object or character (e.g., a face lacking eyes); (c) fusions; (d) transformations/metamorphoses of objects/characters/animals into other elements, which may or may not belong to the same or other categories (e.g., a girl who becomes a small dog). Distortions were considered size distortions when the size of the object or character were non-realistic or were incoherent with respect to the other elements in a scene. Agreement percentage for Scale scoring was >85%. Judges corrected any scoring discrepancies, and the reconciled version was then used for data analysis. We also calculated the number of shape and size distortions present in each report and the relationship between the number of distortions and report length (density evaluation). Report length is codified in the DDB as number of Temporal Units (TU). A temporal unit is defined as whatever activities could synchronously occur and are not described as having occurred successively (Foulkes & Schmidt, 1983). We considered density of both size and shape distortions, given that several studies have shown a positive correlation between bizarreness and report length (Antrobus, 1983; Auld et al., 1968; Hunt et al., 1993; McCarley and Hoffman, 1981; Wood, Sebba, & Domino, 1989–1990). Table 1 Number of DDB reports with bizarreness, number and percentage of reports with size and shape bizarreness, number and percentage of size bizarreness, number and percentage of shape bizarreness SO
St.2
SWS
REM
Total
Significant comparisons
No. of dream reports
230
77
129
391
827
No. and percentage of dream reports with general bizarreness
65, 28.26%
50, 64.93%
72, 55.81%
204, 52.17%
391, 47.28%
SO < SWS (p < .0005), SO < REM (p < .0005), SO < St.2 (p < .00001), REM < St.2 (p < .05)
No. and percentage of dream reports with size and shape bizarreness
12, 18.46%
16, 30.00%
10, 13.89%
25, 12.95%
63, 16.11%
St.2 > REM (p < .001), St.2 > SWS (p < .05)
No. and percentage of dream reports with size bizarreness
9, 13.85%
11, 24.00%
8, 11.11%
22, 10.29%
50, 12.79%
No. and percentage of dream reports with shape bizarreness
9, 13.85%
8, 16.90%
4, 5.55%
12, 5.88%
33, 8.44%
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Qualitative analysis of bizarreness was conducted on report texts and on an interview that is routinely conducted in the sleep laboratory immediately following free recall, in order to clarify any unclear aspects of images or scenes described in the participants’ initial verbalizations. Statistical analyses were run with either Chi square or ANOVA, as required. Results were considered significant at p < .05. All tests were performed as non-repeated measures. 3. Results 3.1. Quantitative analysis As to frequency of bizarreness we examined bizarre dream reports from all sleep stages considered globally. Nevertheless, we also observed significantly different frequencies across sleep stages: SO presented fewer bizarre dream reports than REM sleep (v2 = 12.23, p < .0005), SWS (v2 = 13.99, p < .0005), and St.2 (v2 = 33.12, p < .00001). REM presented fewer bizarre dream reports than St.2 (v2 = 4.22, p < .05) did. Only 63 of the 391 bizarre dream reports examined (12 SO, 16 St.2, 10 SWS, 25 REM) yielded at least one size and/or shape distortion referring to characters, animals, or objects. Given that some reports contained more than one bizarre aspect, the total sample of bizarre features was 83: 50 size distortions and 33 shape distortions. Compared to both the entire sample (7.62%) and the sub-sample of bizarre reports (16.11%), the frequency of reports with shape and/or size distortions was low, independently of sleep stage. That is, nearly one sixth of the dreams judged to be bizarre contained at least one dimensional distortion. Yet, once sleep stage was accounted for, a higher percentage of dream reports with shape and/or size bizarreness was observed for St.2 (30.00%) than for either REM sleep (v2 = 11.57, p < .001) or SWS (v2 = 5.77, p < .05). Results concerning the density of size and shape bizarreness per sleep condition are shown in Fig. 1. Size bizarreness density (.40 ± .49) was significantly higher than shape bizarreness density (.20 ± .36) (t62 = 2.45; p < .05). Yet, once sleep stage conditions were considered, the difference was significant only for REM sleep (t24 = 2.40; p < .05): .45 ± .42 and .09 ± .06, respectively. Two one-way ANOVAs (sleep conditions: 4 levels) were then run separately for each dimensional distortion, and results showed that density of size distortions did not differ per sleep condition, whereas significant differences emerged for shape distortion (F3,59 = 3.92; p < .05). The post hoc analysis (Tukey for unequal samples) revealed that the density of shape distortions in SO was greater than in the REM condition (p < .05). Certain recurring modalities in the appearance of dimensional distortions during dreaming, were detected: As to size distortions, enlargement phenomena were observed in 83% of all examined cases, whereas the shrinking of single elements in relation to oneiric scene context were present in 17% of the reports considered. Fusions accounted for 54% of all shape anomalies noted, whereas metamorphoses accounted for 33%; both types of distortions were equally subdivided between intra-categorical and inter-categorical modifications. Given that the sample size did not allow for further statistical analyses, these data were used in the qualitative appraisal of the two distortion typologies. 1.2
mean density
1 0.8 size shape
0.6 0.4 0.2 0 SO
St2
SWS
REM
sleep stages Fig. 1. Mean density of size and shape bizarreness across sleep stages.
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3.2. Qualitative analysis 3.2.1. Size distortions In some instances a single element filled the entire visual screen with a badly defined, or even an empty background. Indeed, there was no reference system that might allow for estimations of size relative to other objects in the scene, but there was a type of ‘‘zoom effect’’ on a single percept. Ex. n. 1 ‘‘. . . then the size of the backpack, it seemed truly enormous to me, gigantic as if a whole person could fit into it... it was as if I was practically looking into the backpack, right inside the backpack, as if it was framed by another television camera that was entering into the backpack; the whole scene was completely filled with the image of this backpack into which I was looking. . .’’ Ex. n. 2 ‘‘. . . a personldots has a small reptile attached to their foot, it’s not really a reptile but a sort of crocodile, but tiny, however as time goes by, bit by bit, it becomes bigger and bigger until it becomes a normal crocodile. . ..’’ Ex. n. 3 ‘‘. . . I was in a hospital corridor, it was the department where I work as an intern, and I saw many white gowns, a lot of people who were walking, then, from the entrance an enormous person entered, really big—a gigantic person, who filled the whole doorway, I couldn’t fit him into the frame, I only saw outlines, margins. . .’’ In one instance, image enlargement was such to prevent the image from completely fitting into the visual field, and fragments of the entire image were presented as a series of frames. Ex. n. 4 ‘‘. . . in the stream there was a long snake: really, really, really long. . . it was so long! When I saw it, it was as if I was looking at a photo; as if I saw frames of the photo and then I see. . . in the first photo frame there was a head and part of the body, but no tail, all the rest of the snake was in the following frames. . .’’ In other instances, size distortion was noticeable despite the presence of a background in the scene and/or other objects that should serve as parameters for establishing correct relations among the various elements and their organization, in relation to the background. Ex. n. 5 ‘‘. . . there was a small basket, but I saw that a normal-sized horse passed through every now and then, after a while though, that same basket was full of cats, despite the fact that it was small, it was full, there were probably about 10 cats, I remember that there was the mother and all her litter. . .’’ (in the dream I was astonished and sad to see that there could be so many cats in such a small basket) Ex. n. 6 ‘‘I was in a lane, and I stopped to speak to a person who had an enormous head with a large disproportion between head and body; he was a very odd person; his head was as large as the shoulders, about one meter. . ..I was not surprised by the fact that he had such an enormous head, I was considering this as if it were a normal situation.’’ 3.2.2. Shape distortions The most common instances of shape bizarreness were fusions of perceptual characteristics belonging to various objects, characters, or animals within the same semantic category. In the following example the fusion occurs between the characteristics of different animals: a dog, a crustacean, and a feline: Ex. n. 7 ‘‘. . . it was an animal, like a dog, but it was more like a monster because it was kind of. . . it didn’t have any hair, it was as large as a dog, but it was as smooth as a shellfish, it was polished and hard. I don’t know . . .really large teeth and claws and. . .’’ In the following examples, the typical characteristics of two objects from the same category are combined into a more general type of bizarreness: Ex. n. 8 ‘‘. . . I was trying to put a cork stopper into a bottle, there’s a hammer in my hands, but as I wasn’t able to hammer it in, I was thinking of sharpening the cork with a tool. The bottle was a beer bottle, but it had the shape
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and the top of a champagne bottle, with the cork held in place with wire threads’’. (I found the bottle strange; not the fact that I wanted to hammer the glass.) Ex. n. 9 ‘‘. . . gigantic chair-lifts passed by, but they were different from normal chair-lifts as there were so many people inside. . .’’ (it had the shape of an enormous chair-lift, but it contained much more people: like a cableway)’’. In other instance, clear disassociations between the meaning of the object and its image were observed: Ex. n. 10 ‘‘my partner had a camera to take black and white photos, it was weird, it had the shape of a giant keyring, not of a camera’’ (it was identical to an old key-ring that I have in a drawer). Ex. n. 11 ‘‘Two friends and I had to put suitcases, packages, into the car. These packages that we loaded had the shape of human body organs’’. At times the fusion of characteristics belonging to several characters did not occur in a synchronized fashion but in a close temporal succession. The element that is responsible for the distortion in the following example is the accelerated activation of three faces attributed to a single character, who continued to maintain the same role and spatial location in the dream: Ex. 12 ‘‘. . . at the beginning, when he entered’’ (a reference to the boy with whom the participant dreams of arguing), ‘‘his face is interchangeable with that of two other people, it’s really always him, but represented by three different people . . . each face is replaced in sequence. . .’’ Metamorphoses were also noticed among shape distortions, i.e., unexpected transformations of objects/animals/characters into elements of the same of a different category. Ex. 13 ‘‘. . . I had previously massaged him with a strawberry cream that was similar in form to a book. . . the cream in the shape of a book was in a bookcase with many other books, which, however, once taken down from the bookcase could be used as creams. . . the books, while they were on the bookshelf were books, then once removed became creams. . .’’ Ex. 14 ‘‘. . . opposite my house there is a garden. . . so I look out the window and I see the girl who I used to go into the yard with when I was young. . . after looking for a while I realize that she notices me, and at this point she transforms into a dog and as soon as she notices me, she starts to wag her tail and she raises two of her legs in order to draw herself nearer to the window. . .’’ Ex. 15 ‘‘. . .I could see a room. . . I had a very narrow visual field, I saw a table in the center of the room. . .. but immediately I turned to face the center of the table and I saw a small doll on it, it was a person, probably a woman dressed like a doll, with the dimensions of a doll, who, as soon as she saw me, I mean, as soon as she noticed that I was watching her, she camouflaged herself, she was a brunette, she stiffened, trying to transform herself into a doll. . .’’. The generation of impossible shapes in the following example is the result of an attribution of anthropomorphous characteristics to objects: Ex. 16 ‘‘. . . of the merchant ships, there is one in particular and. . . from above the bridge of this ship there were colored eggs with small arms, and legs which dipped into the water. . . there were only these eggs that played like children taking a dip. . .’’. 4. Discussion Taking into account the low frequency of the size and shape distortions of dream images observed we cannot discuss the results in terms of sleep stages or cycles of sleep. So only speculative hypotheses on qualitative analyses will be advanced.
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4.1. Bizarreness as size distortion Size distortion refers to phenomena such as the enlargement or shrinking of single objects or characters, as compared to the relative dimensions of other contextual elements (e.g., a small basket, in which a normal-sized horse was occasionally able to fit, and ten cats, too). Representations of elements reported by participants as being of different dimensions than what they normally perceive during wakefulness are also considered size distortions (e.g., an enormous backpack in which an entire person could fit). From a cognitive perspective, imagery models (Kosslyn, 1983, 1994) could be used to qualitatively investigate oneiric size distortion. From a structural point of view, a mental image is made up of both a superficial representation yielding up phenomenal evidence to our experience and a deep representation containing analogical-propositional information (which is activated from long-term memory for representation of the mental image). Imagery theories have postulated the existence of a visual buffer with the functional characteristics of a perceptual tableau. It is thought that in this perceptual screen, size constraints must be consistent with the relationship among elements. We can reasonably suppose that dream generation also involves representation in the visual buffer of a number of objects and/or characters, whose dimensions must be continuously reset as the narrative advances. This process operates through image enlargement and shrinking, based on cues of depth, figure-background organization, and the relationship among elements that are simultaneously present in the scene. Images must be maintained through a process of visual rehearsal if these operations are to be possible in the absence of perceivable objects. In some circumstances, scarcity of contextual information serving as a background to organize the various elements could render size adjustment operations in a scene more difficult. This phenomenon would therefore create ‘‘zoom’’ or shrinkage effects, the perceptive rendering of which could give rise to an experienced phenomenon of size incongruence within the entire narrative sequence. In other situations, where contextual information is present, size bizarreness could result from a desynchronization in image and image-background rehearsal processes. The link among the images themselves, the images and background, and the sequence of the images throughout the visual narrative may produce a phenomenal experience that is bizarre. The visual buffer activity is a part of Working Memory activity—i.e., of a memory system that is less engaged during sleep than during wakefulness (Braun et al., 1997; Occhionero, 2004). This prevalent involvement of WM in the definition of image size might account for the quantitative differences that can be observed in size and shape distortions for all sleep stages. 4.2. Bizarreness as shape distortion Shape distortion refers to the presence of at least one anomalous element in the shape of an object or a character, i.e., fusions, the attribution of incoherent meaning, and the creation of unlikely objects. We also included metamorphoses—though perhaps not entirely legitimately—in our operative concept of shape bizarreness, i.e., when bizarreness involves sudden and inexplicable transformations of objects or persons through time. (We did not, however, consider unexpected changes of location.) One might account for shape distortions by referring to the involvement of mnemonic trace retrieval processes, which are activated from long-term memory systems for dream generation. As frequently reported in the memory literature, various verbal and visual types of information are encoded according to specific modalities in each particular subsystem: the (pre-semantic) Perceptual Representation System, Semantic memory, and Episodic memory. Memory systems during wakefulness normally operate in parallel integratedly (Schacter & Tulving, 1994). Yet, a dissociation between memory systems, or a desynchronization in the activation of memory systems, might occur during sleep, due to the particular psychophysiological condition in which the cognitive processes required happen to be functioning. Specifically, the proposal is that this phenomenon takes place between the Perceptual Representation System (where object shapes are encoded independently of meaning) and the Semantic or Episodic systems (where shape meanings are encoded). This phenomenon appears to be particularly frequent during Sleep Onset (when we observed a higher shape distortion density than we did for REM sleep). The nature of Sleep Onset images, which are frequently rapid sequences of hypnagogic hallucinations unrelated to a spatio-temporal context, could account for this event. Yet, we are also unable to explain why the density of Stage 2 feature distortions we observed were more
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frequent than they were in other sleep stages. This latter finding, however, is consistent with analogous data yielded by a previous study (Cicogna, Natale, Occhionero, & Bosinelli, 1998). 4.3. Bizarreness and phenomenal consciousness in dreams We agree with Revonsuo (Revonsuo, 1999; Revonsuo & Tarkko, 2002) that phenomenal consciousness in dreams and in wakefulness is due to the coherent binding of single elements. The concept of binding has gained ever greater attention over the last few years in Neuroscience (Kahn et al., 1997), in Cognitive Science (Treisman, 1996), and in Consciousness studies. In its broadest sense, binding refers to the ability of the mind and brain to produce coherent, integrated representations of the world, even though external/internal information is received in multiple forms (Revonsuo, 1999). From a cognitive perspective, it refers to the integration of input from distributed modular processing; and in consciousness studies, binding denotes the integration of phenomenal contents into a unified awareness. Hence, the unity of consciousness most probably depends on underlying neural and cognitive binding mechanisms. Awareness-related binding can be described as an ongoing mechanism, which is grounded on integrative (neural and cognitive) mechanisms operating at lower levels. Most likely, different types of binding act simultaneously to activate inhibition mechanisms. Thus, bizarreness may be considered an unusual integration of elements in combining images (or bits of information), as the filter represented by judgment and control mechanisms is usually ineffective during sleep. The present study was based on a model of dream generation in which phenomenal consciousness may be considered the product of the binding of information derived from continuous and iterative feedback between the bottom-up activation of mnemonic information from long-term memory (LTM) systems and the topdown activation of images and thoughts that are phenomenally present in the dream experience (see ‘dream generation model’ in Cicogna & Bosinelli, 2001). From this perspective, bizarreness could be generally described in terms of a poor functioning in executive processes (the working memory processes of inhibition and binding) that usually inhibit and combine single inputs yielded up to awareness from the circular process. It is in this sense that binding may be considered a process that gives rise to phenomenal consciousness. The assertion is inconsistent with a recent review of a working memory model in which Baddeley (2000, 2003) proposed the existence of a new component, an episodic buffer, which is thought to provide an interface between the central executive and long-term memory. This component is involved in binding operations, to form integrated episodes into a multi-dimensional code, and is assumed to be accessible to conscious awareness. 5. Conclusions Our study indicates a relatively low bizarre feature rate in dreams. Indeed, single dream images tend to be quite coherent with waking percepts, at least in terms of shape (only about 8% of the bizarre reports contained a shape distortion). These results are in agreement with findings from early experimental studies (Dorus, Dorus, & Rechtschaffen, 1971; Snyder, 1970), which yielded very low levels of bizarreness and further showed that the relatively infrequent bizarreness that occurs does so within the context of coherent dreaming. Information resulting from the simultaneous functioning of various long-term memory systems, and referring to the shape and meaning of dream elements, seems to nearly always overlap with images perceived during wakefulness. The hallucination of waking-like images seems to require less executive process engagement, particularly for binding, than the engagement required by continuous and coherent size updating. Although size distortions are relatively infrequent (only approximately 13% of bizarre reports), context-appropriate size representation seems to involve a high working memory load (visual buffer activity, rehearsal, binding), and therefore components that might be partially ineffective during sleep. As anticipated (see the previous section), an explanation for size alteration might be found in visual buffer capacity for containing images and visual buffer functioning. The oneiric scene unfolds through time: as the various elements filling up the visual screen are gradually activated, they require updating with respect to other images in the context. If rapid image updating does not occur throughout the entire sequence, the perceptive impression of an ill-proportioned object—or an object which requires a succession of images for its complete representation—can linger in the dreamer (see example n. 4). In this instance, it is temporal binding that is not
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working efficiently. In others, perhaps only a few elements—or even a single element on a badly defined or non-existent background—are activated. The absence of a reference background, which would allow the dreamer to estimate the relative size of objects, could provoke a ‘‘zoom effect,’’ such that a single element fills the entire visual screen (see examples n. 1–3). When the scene continues, rehearsal activity for the image maintains its size, and field adaptation processes are not activated. The same effect may occur when size distortion is noticeable, despite the presence of a background and/or other objects that should function as parameters for correct relations among the various elements. In these instances, a sort of erroneous attribution in the sizescaling of the image may be triggered. The image maintains the format in which it was first activated by the perceptual representation system (see example n. 5). Yet, example n. 6 (in which the head is out of proportion to the rest of the body) is more difficult to explain. Perhaps it was due to temporal displacement in image production, i.e., with the head being hallucinated first and the rest of the body afterwards. The body image was then ‘‘adapted’’ to the limited size of the mental screen, as if the head image were being rehearsed in the size of initial hallucination. In all these instances, the perceptual ‘‘error’’ appears to be linked to a lack in temporal integration of visual field elements. As to shape bizarreness, the attribution of an object/character to another object’s/character’s perceptual characteristics may be due to a dissociation between the activation of perceptual characteristics retrieved from the (pre-semantic) Perceptual Representation System and the activation of meaning retrieved from the (declarative) Semantic and/or Episodic memory systems (see examples n. 10 and 11). Conversely, fusions appear to be the result of the binding of various elements that are simultaneously available and which typically are associatively linked (or belong to the same conceptual category) (see examples n. 7–9), or are linked in specific, idiosyncratic ways known only to the dreamer. Other shape inconsistencies, which manifest themselves as rapid metamorphoses, might be due to a phasedifference or desynchronization of memory system activity (see examples n. 13–16). The assumption is one of an acceleration in the production of single images in the process of temporal binding. The images then follow one another with no coherent modification of other elements present in the scene. Moreover, the creation of impossible shapes is perhaps linked to original combinations of bits of information, which are only parts of meaningful shapes. Specifically, mnemonic activation that is not opportunely inhibited can trigger a process of binding, which produces a new shape (features binding). Our results suggest that size bizarreness can be effectively described and explained as the products of an impairment in the temporal binding of images. Although this inefficiency in coherent size integration (which is automatic during waking) occurs rarely, it is probably due to a desynchronization in image production processes. Yet, shape bizarreness, such as the bizarreness produced by feature binding seems to occur in response to two different and non-mutually exclusive phenomena: (a) when inputs are too numerous and associatively distant, given that they originate from a chaotic iterative feedback loop between bottom-up LTM systems activation and top-down dream image activation (Cicogna & Bosinelli, 2001); (b) when inputs lack a perceptive/ semantic link, due to a dissociation in the functioning of LTM systems. The case of metamorphoses, however, appears to be more complex from a processing perspective: the phenomenon most probably occurs when a large amount of input and/or when incoherent inputs are associated with a temporal binding problem. In conclusion, our dream production model proposes that the cognitive constructs of (integrated or dissociated) imagery and memory system activity (including LTM, WM, and binding mechanisms) could account for the specific types of bizarreness examined in the present study. Further investigations into the possibility of removing oneself, while dreaming, from the constraints of waking experience (i.e., the temporal and spatial laws of physics (gravity, speed, etc.), logic, story grammar, etc.) should guide future research, with the aim of better understanding mind functioning during various states of consciousness. References Antrobus, J. S. (1983). REM and NREM sleep reports: comparison of word counts by cognitive classes. Psychophysiology, 20, 562–568. Auld, F., Goldenberg, G. M., & Weiss, J. V. (1968). Measurement of primary-process thinking in dream report. Journal of Personality and Social Psychology, 8(4), 418–426.
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Baddeley, A. D. (2000). The episodic buffer: a new component of working memory? Trends in Cognitive Science, 4, 417–423. Baddeley, A. D. (2003). Working memory: looking back and looking forward. Nature Reviews. Neuroscience, 4, 829–839. Braun, A. R., Balkin, T. J., Wesesten, N. J., Carson, R. E., Varga, M., Baldwin, P., Selbie, S., Belenky, G., & Herscovitch, P. (1997). Regional cerebral blood flow throughout the sleep–wake cycle An H215O PET study. Brain, 120, 1173–1197. Cavallero, C., Cicogna, P., Natale, V., Occhionero, M., & Zito, A. (1992). SWS Dreaming. Sleep, 15(6), 562–566. Cicogna, P. C., & Bosinelli, M. (2001). Consciousness during dreams. Consciousness and Cognition, 10, 26–41. Cicogna, P., Cavallero, C., & Bosinelli, M. (1991). Cognitive aspects of mental activity during sleep. The American Journal of Psychology, 104(3), 413–425. Cicogna, P., Natale, V., Occhionero, M., & Bosinelli, M. (1998). A comparison of mental activity during sleep onset and morning awakening. Sleep, 21, 462–470. Colace, C. (2003). Dream bizarreness reconsidered. Sleep and Hypnosis, 5(3), 105–128. Domhoff, G. W. (2005). Refocusing the Neurocognitive approach to dreams: a critic of the Hobson vs Solms debate. Dreaming, 15, 3–20. Dorus, E., Dorus, W., & Rechtschaffen, A. (1971). The incidence of novelty in dreams. Archives of General Psychiatry, 25, 364–368. Foulkes, D., & Schmidt, C. (1983). Temporal sequences and unit composition in dream reports from different stages of sleep. Sleep, 6, 265–280. Foulkes, D. (1985). Dreaming: A cognitive-psychological analysis. Hillsdale, NY: Erlbaum. Foulkes, D. (1999). Children’s dreaming and development of consciousness. Cambridge, MA: Harvard University Press. Freud, S. (1900). Die Traumdeutung. Vien: Franz Deuticke. Hobson, J. A. (1988). The dreaming brain. New York: Basic Books. Hobson, J. A., & Stickgold, R. (1995). The conscious state paradigm: A neurocognitive approach to waking sleeping and dreaming. In M. S. Gazzaniga (Ed.), The cognitive neurosciences. Cambridge, MA: MIT Press. Hobson, J. A., Pace-Schott, E., & Stickgold, R. (2000). Dreaming and the brain: toward a cognitive neuroscience of conscious states. Behavior and Brain Sciences, 23(6), 793–842. Hunt, H. T., Ruzicki-Hunt, K., Pariak, D., & Belicki, K. (1993). The relationship between dream bizarreness and imagination: artefact or essence. Dreaming, 3, 179–199. Kahn, D., Pace-Schott, E. F., & Hobson, J. A. (1997). Consciousness in waking and dreaming: the roles of neuronal oscillation and neuromodulation in determining similarities and differences. Neuroscience, 78(1), 13–38. Kahn, D., Stickgold, R., Pace-Schott, E. F., & Hobson, J. A. (2000). Dreaming and waking consciousness: a character recognition study. Journal of Sleep Research, 9(4), 317–325. Kosslyn, S. M. (1983). Ghosts in the mind’s machine. New York: W.W. Norton. Kosslyn, S. M. (1994). Image and brain: The resolution of the imagery debate. London: MIT Press. McCarley, R. W., & Hoffman, E. (1981). REM sleep dreams and the activation-synthesis hypothesis. American Journal of Psychiatry, 138(7), 904–912. Natale, V., & Esposito, M. J. (2001). Bizarreness across the first four cycles of sleep. Sleep and Hypnosis, 3(1), 18–24. Occhionero, M. (2004). Mental processes and brain during dreams. Dreaming, 14(1), 54–64. Reinsel, R., Antrobus, J. S., & Wollman, M. (1992). Bizarreness in dreams and waking fantasy. In M. Bertini & J. S. Antrobus (Eds.), The neuropsychology of sleep and dreaming (pp. 157–183). Hillsdale: LEA. Revonsuo, A. (1999). Binding and the phenomenal unity of consciousness. Consciousness and Cognition, 8, 173–185. Revonsuo, A., & Tarkko, K. (2002). Binding in dreams. Journal of Consciousness Studies, 9(7), 3–24. Seligman, M. E. P., & Yellen, A. (1987). What is a dream? Behavioral Research Therapy, 1(25), 1–24. Schacter, D. L., & Tulving, E. (1994). Memory systems 1994. Cambridge, MA: MIT Press. Snyder, S. (1970). Phenomenology of dreaming. In L. Madow & L. Snow (Eds.), The psychodynamic implications of the physiological studies on dreams (pp. 124–151). Springfield, IL: Thomas. Treisman, A. (1996). The binding problem. Current Opinion in Neurobiology, 6, 171–178. Wood, J. M., Sebba, D., & Domino, G. (1989–1990). Do creative people have more bizarre dreams? A reconsideration. Imagination, Cognition and Personality, 9(1), 3–16. Zito, A., Cavallero, C., & Cicogna, P. C. (1990). A computer dream data bank. In Abstract book 10th Congress of the European Sleep Research Society, Strasburg, 206. Zito, A., Cicogna, P. C., & Cavallero, C. (1991). DDB: una banca dati per la ricerca sulla fenomenologia del sogno. Giornale Italiano di Psicologia, 5, 781–786.