The effect of presentation format and encoding strategy on associative memory distortion

Revue européenne de psychologie appliquée 69 (2019) 65–72

Disponible en ligne sur

ScienceDirect www.sciencedirect.com

Original article

The effect of presentation format and encoding strategy on associative memory distortion L’influence du format de présentation et de la stratégie d’encodage sur les distorsions de la mémoire associative J. Olszewska a,∗ , J. Ulatowska b,∗ a b

Psychology Department, University of Wisconsin-Oshkosh, 800 Algoma boulevard, Oshkosh, WI 54901, USA Department of Psychology, Nicolaus Copernicus University, ul. Fosa Staromiejska 1a, 87-100 Toru´ n, Poland

a r t i c l e

i n f o

Article history: Received 4 December 2013 Received in revised form 21 August 2018 Accepted 7 March 2019 Keywords: Memory distortion Semantically related words Encoding strategy Format of presentation

a b s t r a c t Introduction. – Previous studies using semantically related words revealed more accurate memory when the items were encoded visually rather than auditorily and when mental images were created during encoding. However, how the level of memory distortion is affected by the creation of different mental imagery formats or by techniques that should suppress generation of mental images has rarely been investigated. Objective. – The aim of the present studies was to investigate the ways in which the encoding strategy affects the accuracy of memory reports for two presentation formats of semantically related words: verbal and pictorial. Method. – In experiment 1, the participants were asked to memorize either pictures or their verbal equivalents (words) from the same category, using one of two encoding strategies: uttering the words or counting backwards. In experiment 2, pictorially or auditory presented material was encoded together with the creation of either visual or auditory mental images of the items. The results of the experimental groups were compared to control groups that received no specific instruction. Results. – Higher levels of false recognition, together with lower rates of correct recognition, were observed for words, presented either visually or auditory, relative to pictures. Moreover, self-generation of additional code during the processing of information favored the reduction of false recognitions. Conclusion. – Encoding strategies that engaged dual coding reduced false recognition. The results are discussed within the distinctiveness heuristic phenomenon. © 2019 Elsevier Masson SAS. All rights reserved.

r é s u m é Mots clés : Erreurs mnésiques Mots reliés sémantiquement Stratégie d’encodage Format de présentation

Introduction. – Des études précédentes utilisant des mots sémantiquement liés ont révélé que la mémoire était plus précise lorsque les éléments mémorisés ont été encodés visuellement plutôt qu’auditivement, et quand des images mentales ont été créées au moment de l’encodage. Cependant, il a rarement été étudié dans quelle mesure le niveau de précision de la mémoire est affectée par le format de création de différentes images mentales ou par des techniques menant à supprimer la création des images mentales. Objectif. – L’objectif des présentes études était de vérifier dans quelle mesure la stratégie d’encodage affecte la restitution de deux formats de mots sémantiquement liés: verbal et pictural. Méthode. – Dans l’expérience 1 il a été demandé à des participants de mémoriser soit des images, soit leurs équivalents verbaux (mots) de la même catégorie en utilisant l’une des deux stratégies d’encodage suivante: prononcer les mots ou compter à rebours. Dans l’expérience 2, le matériel picturalement ou auditivement présenté était encodé avec une création d’images mentales visuelles ou auditives. Les résultats des groupes expérimentaux ont été comparés à un groupe témoin qui ont rec¸u aucune instruction spécifique. Les résultats des groupes expérimentaux étaient comparés à ceux de groupes contrôles qui ne recevaient aucune consigne spécifique.

∗ Corresponding author. E-mail addresses: [email protected] (J. Olszewska), [email protected] (J. Ulatowska). https://doi.org/10.1016/j.erap.2019.03.004 1162-9088/© 2019 Elsevier Masson SAS. All rights reserved.

66

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

Résultats. – Un plus grand nombre de fausses reconnaissances ainsi que des taux plus faibles de reconnaissances correctes ont été notés concernant les mots présentés visuellement ou auditivement plutôt que les images. De plus, l’auto-génération de code supplémentaire pendant le traitement de l’information a favorisé la réduction des fausses reconnaissances. Les stratégies d’encodage qui ont suscité l’analyse la plus approfondie ont réduit le nombre des cas des fausses reconnaissances. Conclusion. – Les résultats obtenus ont été discutés dans le cadre du phénomène de l’heuristique de distinctivité. ´ ´ © 2019 Elsevier Masson SAS. Tous droits reserv es.

1. Introduction Human memory is not a faithful reflection of the past. In fact, memories may differ dramatically from true events leading to “false” memories either in part or in their entirety, reflecting their constructive nature (Bartlett, 1932). The ease of inducing false memories has been a subject of interest for various research paradigms. One of these is the Deese–Roediger–McDermott paradigm (DRM; Deese, 1959; Roediger & McDermott, 1995), in which participants are asked to memorize lists of semantically related words (e.g., table, desk, legs, bench), which remain in a strong semantic relationship with a so-called critical lure (e.g., chair), that is not included in the list. It turns out that the critical lure is often just as likely to be recalled at the retrieval as the other words, which are present in the list. Associative memory distortions are also visible in the category repetition procedure, which uses words that belong to the same category (Dewhurst, 2001; Dewhurst & Anderson, 1999). Dewhurst and Anderson (1999) showed participants one, four, or eight words from the same semantic category and showed that the rate of falsely recognized critical lures increased with the number of words studied. Just as in the case of perceptual illusions, memory illusions of this type occur automatically and are very difficult to avoid. Even when participants are warned about the possibility of this kind of associative memory error, false recollections are not completely eliminated (McDermott & Roediger, 1998; Westerberg & Marsolek, 2006). Currently, the attention of researchers is focused on identifying the mechanisms that contribute to the emergence and reduction of the above distortions. Previous studies on associative memory errors revealed better functioning of memory when the memorized items were encoded visually rather than auditorily (Hege & Dodson, 2004; Howe, 2006; Israel & Schacter, 1997; Lloyd, 2007; Schacter, Cendan, Dodson, & Clifford, 2001). Israel and Schacter (1997) found that the encoding of words together with their images led to more distinctive recollections, and, consequently, to a lower rate of memory distortions than when encoding words alone. Dodson and Schacter (2001) demonstrated that young and older adults who encoded images (black-and-white sketches) or images combined with verbal labels had lower rates of false recognition of non-studied words. The main explanation for such an effect is the distinctiveness heuristic, defined as a meta-mnemonic process consisting in the retrieval of information concerning certain perceptual details that were present at the encoding stage (Israel & Schacter, 1997). If these additional perceptual details are not present during retrieval, a word is not recognized as one that occurred in the studied list (Dodson and Schacter, 2001; Israel & Schacter, 1997; Strack & Bless, 1994). More characteristically, distinctive information (or a specific way of information processing) reinforces the encoding of data specific to a given item (Howe, 2006). In other words, distinctiveness can benefit memory by helping to avoid memory errors, such as misremembering the details of prior experiences, or falsely remembering

events that did not occur since these experiences or events do not contain enough detailed and specific information. Apart from research using perceptual materials in order to increase distinctiveness, there is a group of studies in which, a reduction in false recall and recognition rates resulted from different encoding instructions (e.g., Foley, Wozniak, & Gillum, 2006; Kellogg, 2001). One of the key elements turned out to be the use of imagery encoding. Generating mental images during encoding significantly reduced the rate of false recollections of verbal semantic associates (Foley, Hughes, Librot, & Paysnick, 2009; Gunter, Bodner, & Azad, 2007; Olszewska & Ulatowska, 2013). The self-generated mental images most probably increase the distinctiveness of encoded verbal material, which is also consistent with the dual coding approach (Paivio, 1986). It is, thus, well-established that both the encoding of pictorial material and self-generation of additional pictorial code while studying verbal material, leads to a better discrimination of studied words and lures as compared to simple encoding without any self-generation. Self-generated additional codes also increase correct recognition and recall, revealing a mirror effect (more correct responses and fewer false responses) (Glanzer & Adams, 1990). It is not clear, however, whether imagery encoding is equally effective when a complementary code is created on the basis of different modality (e.g., when stimuli are presented auditorily and selfgenerated code refers to images creation), or when self-generated code shares features from the modality of encoded material (e.g., when stimuli are presented in a verbal written format and selfgenerated code is creating images of this verbal description). The latter assumption is based on results from other memory paradigms where producing a word aloud during encoding enhances memory performance, as compared to reading a word silently (so-called production effect; e.g., Conway & Gathercole, 1987; Gathercole & Conway, 1988; MacLeod, Gopie, Hourihan, Neary, & Ozubko, 2010). This effect is, however, limited to a withinsubjects manipulation, as, in order to be valuable at retrieval, the distinctiveness has to be experienced directly at encoding (MacLeod et al., 2010). Furthermore, Brooks (1967) described the conflict between reading information (visual task) and visualizing its content, suggesting selective interference. Similar disruption did not occur when participants had listened to information (auditory task) instead of reading. Corresponding results were obtained by De Beni and Moe (2003) – imagery increased recollection of the oral material better than the written (i.e., visual) material, suggesting that interference occurs when two tasks require the same modality. Given all of the above, there is evidence that increasing item distinctiveness by self-generating additional code at encoding should favor memory performance toward an increase of correct recognition (hit rate) and a decrease of false recognition (false alarms rate). However, to the best of our knowledge, no empirical research exists addressing the question of whether such manipulations are equally effective when applied to different formats of semantically associated stimuli. In the current studies, we attempted to address this

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

issue directly, by comparing memory for two types of stimuli – verbal and pictorial. In experiment 1, we tested if articulation while encoding would be beneficial for both types of material. It was assumed that, on the one hand, articulation applied to pictures should result in creating additional phonological code that is different in its nature from the pictorial one. Thus, articulation should increase memory performance for pictorially encoded stimuli. On the other hand, although using articulation while studying verbal material (words) would also result in self-generated code, this might be not enough to increase memory accuracy as both tasks, reading and articulation, would be performed by means of the same system (i.e., phonological) (Brooks, 1967; De Beni & Moe, 2003; Paivio, 1971). Articulation strategy was compared to two other conditions. The first one required participants to count backward, which engaged the phonological loop and possibly suppressed spontaneous generation of additional codes (see Olszewska & Ulatowska, 2013), leading to a decrease in memory performance. The second, control condition required participants to memorize words without any specific study directions. We assumed that the participants in a control condition might reveal relatively high memory performance due to using self-elaborated memorizing techniques (see Olszewska & Ulatowska, 2013). In experiment 2, we aimed to investigate whether the improvement of memory performance caused by self-generated imagery code (Foley et al., 2006; Olszewska & Ulatowska, 2013) would be similar for verbal and pictorial semantically related encoding material. Based on dual coding theory (Paivio, 1986) and previous studies on imagery encoding (e.g., De Beni and Moe, 2003), we assumed that imagery instruction would only be beneficial if the self-generated imagery code differed in terms of modality from the stimuli encoded.

2. Experiment 1 Previous research has shown a reduction in false memory formation following pictorial presentation (e.g., Israel & Schacter, 1997). In addition, generating an additional code during memorizing should increase memory accuracy and possibly decrease false memories (e.g., Paivio, 1971). Thus, we predicted that: • irrespective of the memorizing strategy, the encoding of verbal semantic associates will cause greater memory distortions than the encoding of pictorial material; • irrespective of the type of material, encoding combined with the loading of the phonological loop with another task will cause an increase in the number of memory distortions, whereas encoding involving the activation of the acoustic code will act opposite.

2.1. Method 2.1.1. Participants The participants in the study were 126 undergraduate students (age: M = 21.42, SD = 3.91; 81% women, 19% men).

2.1.2. Materials The first stage of the study was the preparation of stimulus material. Due to potential cultural differences and abstractness of some words, it was impossible to use original DRM lists or Russel and Jenkins’ (1954) word association norms. For these reasons items from six selected categories were used (i.e., fruit, vegetables, clothes, animals, kitchen equipment, and computer equipment)

67

and a pilot study was carried out with 26 participants1 , aimed at creating lists containing the most representative items from these categories. The participants were presented with the names of these categories and asked to give the first association that a given category brought to their minds. They were also asked not to generate abstract words. Next, a list of most frequently appearing items was compiled for each category. Based on the pilot study, six lists of words were made to be used in the main study. Just like in the DRM paradigm (Roediger & McDermott, 1995), each list was composed of 12 words – the items that were easy to visualize and the most popular in a given category, except the word that had the largest number of appearances in the pilot study (the prototype). In the recognition phase, the prototype word served as the so-called critical lure (a word semantically associated with a given list but not present during the encoding phase). Thus prepared, the lists were presented to the participants, depending on the condition they were allocated to, either as visual material2 (a photo illustrating a given word) or as verbal material (a given word written in letters). In the “pictorial” condition, participants were shown a presentation containing color photos of items from lists, placed on a white background. The photos were centered and occupied about 50% of the slide. In the “verbal” condition, verbal equivalents of items from lists were written in black 44-point Calibri type. They were centered and placed on a white background. In both conditions, each of the slides presenting a word or a photo was shown for two seconds and was followed by a blank screen with a white background appearing for another two seconds. The words or photos were arranged in categories in the same order. The recognition test was based on tests used in the DRM paradigm (Roediger & McDermott, 1995, experiment 1). It comprised 42 items: 12 memorized earlier (two from each category) and 30 new probes. The latter included three kinds of items: 6 critical lures (prototypes of each category, e.g., apple), 12 items whose semantic associations with the lists were weak (2 for each list) and 12 items unrelated to any of the six categories. Just like in the case of lists in the DRM paradigm, lures weakly associated with a category were selected from among those that ranked 13th or below in the pilot study (e.g. Roediger & McDermott, 1995). Items in the recognition test were presented in random order in the same modality as the lists during information encoding (verbally or visually). Each word or photo was shown for four seconds and was followed by a blank screen appearing for another four seconds. 2.1.3. Procedure and design The experiment had a 3 (encoding strategy: whispering vs. counting backwards vs. control) × 2 (material format: verbal vs. pictorial) between-subjects design. The key dependant variables were: a false alarms rate to critical lures (i.e., the proportion of “yes” responses to critical lures) and a hit rate (i.e. the proportion of “yes” responses to studied items). Additionally, two false alarms rates to foil items were also analyzed (i.e., the proportions of “yes” responses to unstudied, non-critical items that are either weakly related or unrelated to the lists). Participants were randomly allocated to the experimental conditions and examined in small groups. They were informed that they would be taking part in a memory study and that they would be presented with several lists, each containing 12 items that they would have to memorize in a particular way. Depending on the material format condition,

1

These individuals did not take part in the main study. All the photos used were subjected to another pilot study, in which 21 judges were asked to name the object presented in each of the photos so as to check whether their interpretation corresponded with the experimenters’ assumptions. Consensus between the judges was high and equalled 97.3%. 2

68

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

participants were asked to carefully study either a series of words (N = 59) or photos (N = 67). Additionally, in each of these two conditions the encoding strategy was manipulated between-subjects, that is, while encoding participants were asked either to: • whisper the name of each item until it disappeared from the screen and to do the same for each word or photo appearing or; • to count backwards, whispering every second number starting from 1000, without interrupting this activity during the entire presentation or; • to memorize the presented items (the control group, without an additional instruction). The combination of encoding strategy (counting backwards, uttering a word and control) and presentation format (verbal and pictorial) resulted in six between-subjects conditions. After the presentation of the last list, the participants were asked to solve simple mathematical tasks for two minutes. After that time elapsed, the participants received an answer sheet with numbers from 1 to 42 and were requested to watch a presentation with a recognition test. Their task was to decide, in the case of each item from the presentation, whether a given word or photo had been shown to them before, during the study phase. They were to mark their decisions on the answer sheet. 2.2. Results and discussion In order to check the influence of various instruction types and information presentation modalities on the false alarms rate to critical lures, analysis of variance was performed in a 3 (encoding strategy) × 2 (material format) between-subjects design. Where multiple comparisons were conducted, a Bonferroni correction was applied. The analysis showed a significant main effect of encoding strategy, F(2, 120) = 56.38, p < .001, ␩2 = 0.48. The post hoc analysis concerning the strategy of encoding showed that the participants who counted backwards during encoding had the highest rate of false alarms (M = .58, SD = 0.23), which differed significantly from the rate obtained by the group naming objects (M = .13, SD = 0.21), as well as from the control group, which did not use any particular technique (M = .23, SD = 0.23). Differences between the last two groups were also statistically significant. Also significant was a main effect of material format, F(1, 120) = 19.56, p < .001, ␩2 = 0.14. As predicted, the participants who encoded and recognized photos had much fewer false alarms to critical lures (M = .24, SD = 0.25) than individuals presented with verbal material (M = .39, SD = 0.32). The interaction of the two factors turned out not to be statistically significant, F(2, 120) = 0.63, p = .535. The means for each group are presented in Table 1. Table 1 Mean proportion of false alarms and hits as a function of presentation format and encoding strategy in experiment 1. Response type

Format

Strategy

Mean

SD

FA critical items

Picture

Counting Naming Control Counting Naming Control Counting Naming Control Counting Naming Control

0.51a 0.02b 0.17c 0.66a 0.24b 0.29b 0.68a 0.94b 0.91b 0.67ab 0.60a 0.76b

0.20 0.07 0.13 0.26 0.24 0.28 0.20 0.11 0.16 0.20 0.25 0.19

Text

Hits

Picture

Text

Means with different letter indices differ significantly within single simple effect analysis.

The rate of his was also analyzed. The lowest level of hits was found for the group that counted backwards during encoding (M = .67, SD = 0.19). This rate was significantly lower than that found for the group naming the objects they saw (M = .78, SD = 0.25) and that found for the control group (M = 0.83, SD = 0.19), F(2, 120) = 7.13, p = .001, ␩2 = 0.11. The main effect of the format of memorized material, F(1, 120) = 24.29, p < .001, ␩2 = 0.17 and the interaction of both factors, F(2, 120) = 8.23, p < .001, ␩2 = 0.12 were also significant. The group with the highest hit rate was the one that was asked to name photos, and the group with the lowest hit rate was the one naming written words. The next stage involved checking the rate of false alarms to foil (non-critical) items, both weakly related and unrelated. Analysis of variance showed that only the main effect of encoding strategy was statistically significant for both types of items [weakly related: F(2, 120) = 14.26, p < .001, ␩2 = 0.19; unrelated: F(2, 120) = 16.68, p < .001, ␩2 = 0.22]. The participants asked to count backwards during encoding again obtained a higher rate of false alarms to both types of foil items (weakly related: M = .07, SD = 0.12; unrelated: M = .15, SD = 0.17). Differences between two other groups were not statistically significant (naming: respectively M = .008, SD = 0.03 and M = .03, SD = 0.07; control: M = 0, SD = 0 and M = .02, SD = 0.07). The main effect of material format [weakly related: F(1, 120) = 0.66, p = .419; unrelated: F(1, 120) = 0.15, p = .702], as well as the effect of interaction between the two factors, were not significant [weakly related: F(2, 120) = 0.17, p = .845; unrelated: F(2, 120) = 1.45, p = .237]. Although previous studies suggested that uttering a word should increase memory performance (e.g., Conway & Gathercole, 1987; Gathercole & Conway, 1988), no such effect was obtained in the present study. Self-generation of an auditory code when encoding verbal material did not affect the rate of false alarms to critical lures compared to the condition in which no particular encoding technique was imposed. Similar results were obtained previously (Olszewska & Ulatowska, 2013), and although only speculative it was suggested that the participants from the control group may have used their own encoding strategies, ones that they were well familiar with. In the present study, the control group encoding verbal material had a high rate of hits, but their own encoding strategy was not sufficient enough to effectively reduce the rate of false alarms for critical lures to the level noticed in naming condition. The lack of substantial improvement in recognition in the group employing the technique of whispering the names of objects corresponds with some of the earlier studies (Conway & Gathercole, 1987; Gathercole & Conway, 1988; Hopkins & Edwards, 1972), in which only saying words aloud – rather than just whispering or mouthing them – resulted in their better recognition. Moreover, the advantage of reading words aloud was restricted to a withinsubject design (see Conway & Gathercole, 1987). In the case of using an encoding instruction, which additionally loaded the phonological loop with a task unrelated to the analysis of the memorized material, hit and false alarms rates were similar (.66 and .67, respectively). This is due to the fact that associative memory errors arise very quickly and automatically, which results from activation spreading in the semantic network (Collins & Loftus, 1975). Loading the phonological loop by counting backwards makes participants unable to analyze details of the encoded items and allows them to process the items only superficially, which results in a substantially higher rate of false recognitions. However, according to previous studies (e.g., Thapar & McDermott, 2001), shallow encoding should also inhibit relational processing and decrease the possibility of experiencing lures at study. A possible explanation of the high false alarms rate obtained here is that counting does not distract participants to the extent they are not able to process the meaning of each item. To induce shallow encoding, vowel counting has been typically used, but

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

this technique requires participants to focus their attention on local processes, while counting, although resource consuming, still allows for global word processing (Navon, 1977). As such, relational encoding might have manifested at encoding, leading to a greater reliance on gist at the test. 3. Experiment 2 The results from experiment 1 have shown that activation of the phonological strategy resulted in better memory, particularly for pictures. The aim of experiment 2 was to test whether generation of other codes may also affect memory, resulting in higher accuracy. More precisely, we applied an imagery strategy for both types of material, pictorial and verbal. Based upon the results of experiment 1, we predicted that generating complementary code, different from the one in which material to–be–remembered is encoded, would result in higher memory accuracy. To maintain the verbal nature of memorized stimuli and maximize qualitative differences between encoded material and generated codes, we decided to change the words’ presentation modality from visual to auditory. Encoding written words and imagining their pictorial references engages pool of resources from the same, visual modality. Thus, the effectiveness of such an encoding may be lower than when words are encoded auditorily and additionally their pictorial mental image is created. The latter condition engages pools of resources from two different modalities, possibly leading to the creation of perceptually richer representations. This design would also allow further testing of the superiority of pictorial code. Furthermore, we also aimed at testing the hypothesis, drawn from the results of experiment 1, suggesting that, when no specific instruction was given (control condition), the participants would use their own, well-mastered encoding strategies. 3.1. Method 3.1.1. Participants The participants in the study were 166 undergraduate students (age: M = 21.97, SD = 3.87; 98.1% women). They were offered a gift card for participation. 3.1.2. Materials The same lists of words and pictures as in experiment 1 were used, with the exception that the words were presented auditorily, read by a female voice. The recognition test’s composition was identical to the one from experiment 1. Items in the recognition test were presented in the same modality as the lists during information encoding (auditorily or visually). The test items were presented in a random order for four seconds and were followed by a blank screen, appearing for another four seconds. 3.1.3. Procedure and design The experiment had a 3 (encoding strategy: create opposite modality mental image vs. create verbal label mental image vs. control) × 2 (material modality: pictorial vs. auditory) betweensubjects design. Two dependant variables were analyzed: a false alarms rate to critical lures (i.e., the proportion of “yes” responses to critical lures) and a hit rate (i.e. the proportion of “yes” responses to studied items). Participants were randomly allocated to the experimental conditions and examined in small groups. They were informed that they would be taking part in a memory study and that they would be presented with several lists, each containing 12 items that they would have to memorize. Depending on material modality condition (visual vs. auditory) participants were presented either with a series of photos (N = 79) or were asked to

69

listen to a series of words (N = 87). In each of these conditions participants were randomly divided into three encoding conditions, where they were asked either to create a pictorial mental image of each item presented (i.e., a mental image of a written word) or a mental image that stayed in opposition to the code of presented items (i.e., an auditory mental image of how the words are pronounced in the pictorial condition or a pictorial mental image of each word’s equivalent in the auditory condition). Instructions that asked participants to create a pictorial mental image and a sound-based mental image, required self-generation of codes that stayed in opposition to codes of presented items (visual vs. auditory). Therefore, these instructions were treated as equivalent (i.e., opposite modality creation condition). After the presentation of the last list was over, the participants were asked to solve simple mathematical tasks for two minutes. After that time elapsed, the participants received an answer sheet with numbers from 1 to 42 and were requested to listen to or watch a presentation with a recognition test. Their task was to decide whether each item from the presentation had been shown to them during the study phase. They were to mark their decisions on the answer sheet. After test completion, the participants from two control conditions were asked to write down if they used any mnemonic technique during encoding and, if they did, to shortly describe the technique. 3.2. Results and discussion In order to show the influence of instructions and presentation modalities on the rate of false alarms to critical lures, a 3 (encoding strategy) × 2 (material modality) between-subjects ANOVA was performed. The analysis indicated that there was a main effect of material modality, F(1, 160) = 106.06, p < .001, ␩2 = 0.40 and a main effect of encoding instructions, F(2, 160) = 6.63, p = .002, ␩2 = 0.08. The interaction between encoding instructions and material modality was also significant, F(2, 160) = 8.04, p < .001, ␩2 = 0.09. The main effect of modality indicates that false alarms rate to audio words (M = .44, SD = .32; collapsing across different encoding instructions) exceeded false alarms rate to pictures (M = .08, SD = .10). The main effect of encoding instructions showed a lower rate of false alarms when opposite modality mental image creation was applied during encoding (M = .18, SD = .21) as compared to the verbal label image creation condition (M = .28, SD = .30) and the control condition (M = .34, SD = .36), however, the interaction revealed that this pattern was true for the auditory modality. Simple effects revealed that participants who encoded pictures did not differ in terms of false alarms (all ps > 0.1). As listed in Table 2, false alarms were at a significantly lower rate in those who memorized words auditorily and created visual mental images of their equivalents (ps < .01).

Table 2 Mean proportion of false alarms and hits as a function of presentation format and encoding strategy in experiment 2. Response type

Format

Strategy

Mean

SD

FA critical items

Picture

Opposite modality image Verbal label image Control Opposite modality image Verbal label image Control Opposite modality image Verbal label image Control Opposite modality image Verbal label image Control

0.08 0.09 0.07 0.26 0.47 0.59 0.95 0.94 0.96 0.89 0.78 0.73

0.10 0.09 0.13 0.25 0.32 0.32 0.07 0.07 0.06 0.09 0.15 0.14

Audio

Hits

Picture

Audio

70

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

The rate of hits was also analyzed. Hit rate was submitted to the same ANOVA and it revealed a main effect of material modality, F(1, 160) = 80.31, p < .001, ␩2 = 0.35, indicating higher hit rate following pictorial presentation (M = .95, SD = .07) than auditory presentation (M = .80, SD = .14). A main effect of encoding instructions was also significant, F(2, 160) = 7.52, p = .001, ␩2 = 0.09 revealing differences between condition where participants created opposite modality mental image during encoding (M = .92, SD = .08) and both verbal label mental image creation condition (M = .86, SD = .14) and control condition (M = .84, SD = .16). The interaction between encoding instructions and material modality was also significant, F(2, 160) = 10.27, p < .001, ␩2 = 0.11. In accordance with the assumptions, simple effects showed that encoding instructions only lead to differences in memory performance between participants who encoded auditorily presented material. Specifically, those who selfgenerated pictorial mental images (i.e., opposite modality mental image) were more accurate than those who self-generated mental images of verbal labels, t(58) = 3.72, p < .001, d = 0.98, and those who did not get any instruction, t(56) = 5.27, p < .001, d = 1.41. There was no difference between participants who self-generated mental images of verbal labels and those from the control condition, t(54) = 1.15, p = .254. We expected that the encoding strategy requiring participants studying pictures to create mental images of either written words or sounds would improve memory accuracy. However, we found no significant effect of this manipulation [opposite modality mental image vs. mental images of verbal labels: t(52) = 0.26, p = .796; opposite modality mental image vs. control group: t(49) = 0.93, p = .354; mental images of verbal labels vs. control group: t(51) = 1.28, p = .207] and, thus, we were not able to reject the possibility of a null effect. Although the reported lack of effect is based solely on p levels > .05 (see Cumming, 2014; Ly et al., 2018), it seems crucial to discuss this in the light of existing theories. According to the dual coding theory (Paivio, 1986), it seems reasonable to expect that creating mental images of written words or mental images of how these words sound while articulated would result in additional code formation, and should, thus, increase memory performance. One possible explanation is that the lack of memory improvement is caused by the fact that creating mental images is based on activation of representations, which engages a pool of resources for the same modality as encoded stimuli (pictorial). According to Baddeley (1992), the visuospatial sketchpad allows processing of pictures and images. Therefore, while processing pictures it is difficult to use imagination sufficiently to create distinctive features that could help in rejecting unstudied words during recognition. Another possible, yet speculative, explanation for this lack of memory improvement may

lie in the frequency of using mental images of written words or sound-based mental images. Intuitively, people tend to create mental images of objects rather than mental images of typed texts or mental images of sounds. Thus, this lack of experience could lead to the creation of less distinctive mental images or require more time for encoding. This aspect, although highly plausible, needs more research. It is also possible that lack of significant differences in the pictorial condition is a consequence of the ceiling effect. In accordance with the hypothesis, memory accuracy for pictures was very high, thus, manipulation toward increasing distinctiveness was not noticed, possibly due to the well-documented picture superiority effect (for review and discussion see Paivio, 1971). In addition, as already mentioned, no improvement in memory is inferred following p level > .05, which does not convey information about the size of the effect. Thus, more studies should be done to precisely estimate the presence of the effect. To check whether participants from the two control conditions applied spontaneously their own method of memory boosting, they were asked to provide information about any mnemonic technique they applied during the encoding phase. The short descriptions of techniques were coded into broader categories. In accordance with expectations from experiment 1 (see also Olszewska & Ulatowska, 2013), it was revealed that 78.8% of participants used a kind of mnemonic method. These results suggest that, when not asked to do otherwise, the majority of participants apply their own, probably well-elaborated and previously practiced, memory boosting method. Furthermore, the groups encoding pictures or auditory material did not differ in terms of the frequency of usage of these techniques, Chi2 (5, N = 52) = 6.6, p > .05. As is depicted in Fig. 1, most of the participants declared that they used the categorizing of material during encoding. It is important to remember, however, that the words and pictures were already presented grouped according to their category. 4. General discussion In the presented study, semantic memory distortions were tested in two experiments. Considering the well-established advantage for visual material, particularly when the input format is pictorial (e.g., Israel & Schacter, 1997), it was important to establish whether false memories would vary across different encoding strategies and for material presented either visually, as written words and pictures, or auditorily. The results revealed three data patterns of importance. First, more false alarms to critical lures and a lower hit rate were found when words were memorized, either visually or auditory than when their pictorial equivalents

Fig. 1. Frequency (%) of using various mnemonic techniques in control groups.

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

71

were encoded. Second, the activation of the phonological strategy during the processing of both types of stimuli (verbal and pictorial) favored the reduction of false alarms, however, this was only the case when the input was pictorial (experiment 1). Third, imagery encoding reduced false alarms to verbal stimuli, but not pictorial stimuli (experiment 2).

improvement after visualization of printed words stays in accord with our assumption that the modality of encoding and modality of a self-generated code should differ in order to create differences in the context of similarity.

4.1. Verbal material recognition

In the case of memorizing pictorial material in experiment 1, whispering the name of the object perceived in the photo turned out to be the most effective encoding technique (hit rate: .94; false alarms rate: .03). Articulation produced an acoustic code, which is rich and carries additional perceptual features, leading to longer information retention (Crowder & Morton, 1969; Penney, 1989). In experiment 2, imagining pictures either as written or vocalized labels of these objects did not influence already an accurate memory for these pictures as compared to a control group. A high rate of hits may be explained by dual coding: pictorial and conceptual (Paivio, 1986), which means that many more details were encoded (a mental image and its verbal label). At the recognition stage, the participants were guided by the distinctiveness heuristic. Counting backwards during encoding was intended to suppress or considerably limit spontaneous naming of perceived pictures so that the articulation component was eliminated. When the phonological loop was additionally engaged by this rival task, the rate of false alarms considerably increased, approaching that of hits (.51 and .68, respectively). The results confirmed our predictions and showed that the well-established picture superiority effect (Paivio, 1986) disappears when the phonological loop is engaged by an unrelated task and the creation of additional verbal code is, thus, limited. When no encoding technique was imposed (control groups), high accuracy of recognition was also observed. The results of experiment 1 suggested that it was likely that individuals in the control group employed their own, well-mastered techniques (see also Olszewska & Ulatowska, 2013). Moreover, picture encoding involves spontaneous naming (Paivio, Clark, Digdon, & Bons, 1989), which was confirmed in the post-experimental interview in experiment 2. Over 19% of participants from the control groups, who were asked to list any encoding strategy they applied, declared using repetition of an items’ name as a way of facilitating encoding. Although in experiment 1 these spontaneous encoding strategies were not as effective in reducing false alarms rate as generation of additional auditory code, they were efficient enough to be considered as working in favor of dual coding (Paivio, 1971). This was later confirmed in experiment 2, where no differences were observed between the control group, where a large number of participants applied their own encoding strategies, and two other groups that were instructed to form mental images. The current studies have demonstrated that a similar strategy employed during verbal encoding and pictorial encoding results in different proportions of hits, as well as false alarms. This indicates that encoding strategies are not equally successful in increasing memory accuracy and that their effectiveness depends on their relation to the encoded material. When the encoded material was presented in one modality, an encoding strategy that engaged the same system was ineffective. This was revealed for material encoded pictorially and verbally.

In accordance with predictions, verbal material, presented either visually (experiment 1) or auditorily (experiment 2), was more susceptible to distortions. However, when no encoding strategy was imposed (the control group) the memory performance depended on the format of verbal material presentation, with rates of hits and false alarms of .76 and .29, respectively, if participants encoded verbal material visually (experiment 1), and .73 and .59, respectively, when auditory presentation was applied (experiment 2). These results correspond well with those obtained by Smith and Hunt (1998), who employed visual and auditory presentation of DRM lists. This confirms that visually driven processing is richer and visual stimuli contain more discriminable features as compared to auditory items (Smith & Hunt, 1998; see also Gallo, McDermott, Percer, & Roediger, 2001). Furthermore, the results of experiment 1 imply that the encoding strategy based on articulation (i.e., whispering) is not sufficient to improve memory. One possible explanation is that the strategy requiring whispering of encoded words is a phonological one and refers to the same code as the encoded words, although they are visually presented. In other words, we may state that a self-generated code should probably refer to a different format/modality than encoded words in order to increase memory accuracy, which is, to some extent, consistent with Paivio’s (1986) dual coding approach. The results from experiment 2, in which words were presented auditorily, to some extent, support the above conclusion. Instructing participants to create a mental image of heard words resulted in a lower rate of false alarms, along with a higher hit rate, which depicts a mirror effect (Glanzer & Adams, 1990). These manipulations promoted encoding of more specific features of list items, which differentiated them from one another and from the critical lure, improving veridical item memory and reducing the tendency to misremember a related lure as one that had been studied. However, the improvement toward a lower rate of false alarms and a higher hit rate was only noticed for participants who created a pictorial mental image of encoded stimuli and not a written one. This shows that engaging a different system (i.e., visual) and generating complementary code during lists’ studying resulted in higher memory accuracy and indicates the presence of distinctive item-specific processing. A self-generated code that referred to the same format as encoded stimuli did not induce sufficient item-specific processing. It is consistent with Hunt’s (2003, 2013) theory of distinctiveness, which is described as “the processing of differences in the context of similarity” (Hunt, 2013, p. 11). A list of semantically related words creates a context of semantic similarity to the extent that the critical lure comes to mind either consciously or unconsciously. From this theoretical perspective, the effect of self-generated codes of memorized words has been explained by inferring that a self-generated code in a different form than presented words provides more distinctive cues than the selfgenerated code in a similar form to encoded words (Hunt, 2003, 2013). In experiment 1, self-generated code based on whispering contained the same phonological features as encoded words, therefore, this code did not increase the distinctiveness of encoded items. In experiment 2, however, a self-generated code in a pictorial form served as a more effective basis for subsequent rejection of lures, which lacked these distinctive details. Lack of memory

4.2. Pictorial material recognition

4.3. Limitations and further studies The obtained results constitute a point of departure for further research investigating the influence of various verbal and pictorial information and encoding strategies on the memory performance. This, in turn, will allow for determining more precisely how the processing of verbal information differs from the processing of its pictorial reflection, which has been a subject of controversy among researchers (e.g. Anderson & Bower, 1974; Paivio, 1971; see also

72

J. Olszewska, J. Ulatowska / Revue européenne de psychologie appliquée 69 (2019) 65–72

Goolkasian & Foos, 2002), and comes down to the existence of two models of storage and processing of words and images. Another aspect that may be considered in future studies concerns memory for more abstract (meaningless) material along with different encoding strategies. This would allow for an elaboration on a memory pattern for these stimuli, so it could be further seen if this pattern would be consistent with the pattern that has been obtained for concrete (meaningful) material. Funding This research was supported by The National Science Centre Grant DEC-2011/01/D/HS6/05482. Disclosure of interest The authors declare that they have no competing interest. References Anderson, J. R., & Bower, G. H. (1974). Interference in memory for multiple contexts. Memory and Cognition, 2, 509–514. Baddeley, A. (1992). Working memory. Science, 255, 556–559. Bartlett, F. C. (1932). Remembering: A study in experimental and social psychology. Cambridge, UK: Cambridge University Press. Brooks, L. R. (1967). The suppression of visualization by reading. Quarterly Journal of Experimental Psychology, 19, 289–299. Collins, A. M., & Loftus, E. F. (1975). A spreading-activation theory of semantic processing. Psychological Review, 82, 407–428. Conway, M. A., & Gathercole, S. E. (1987). Modality and long-term memory. Journal of Memory and Language, 26, 341–361. Crowder, R., & Morton, J. (1969). Precategorical acoustic storage (PAS). Perception and Psychophysics, 5, 365–373. Cumming, G. (2014). The new statistics: Why and how. Psychological Science, 25, 7–29. De Beni, R., & Moe, A. (2003). Presentation modality effects in studying passages. Are mental images always effective? Applied Cognitive Psychology, 17, 309–324. Deese, J. (1959). On the prediction of occurrence of particular verbal intrusions in immediate recall. Journal of Experimental Psychology, 58, 17–22. Dewhurst, S. A. (2001). Category repetition and false recognition: Effects of instance frequency and category size. Journal of Memory and Language, 44, 153–167. Dewhurst, S. A., & Anderson, S. J. (1999). Effects of exact and category repetition in true and false recognition memory. Memory & Cognition, 27, 665–673. Dodson, C. S., & Schacter, D. L. (2001). “If I had said it I would have remembered it”: Reducing false memories with a distinctiveness heuristic. Psychonomic Bulletin & Review, 8, 155–161. Foley, M. A., Hughes, K., Librot, H., & Paysnick, A. (2009). Imagery encoding effects on memory in the DRM paradigm: A test of competing predictions. Applied Cognitive Psychology, 23, 828–848. Foley, M. A., Wozniak, K., & Gillum, A. (2006). Imagination and false memory inductions: Investigating the role of process, content, and source of imaginations. Applied Cognitive Psychology, 20, 1119–1141. Gallo, D. A., McDermott, K. B., Percer, J. M., & Roediger, H. L., III. (2001). Modality effects in false recall and false recognition. Journal of Experimental Psychology: Learning, Memory, and Cognition, 27, 339–353. Gathercole, S. E., & Conway, M. A. (1988). Exploring long-term modality effects: Vocalization leads to best retention. Memory & Cognition, 16, 110–119. Glanzer, M., & Adams, J. K. (1990). The mirror effect in recognition memory. Data and theory. Journal of Experimental Psychology: Learning, Memory and Cognition, 16, 5–16.

Goolkasian, P., & Foos, P. W. (2002). Presentation format and its effect on working memory. Memory & Cognition, 30, 1096–1105. Gunter, R. W., Bodner, G. E., & Azad, T. (2007). Generation and mnemonic encoding induces a mirror effect in the DRM paradigm. Memory & Cognition, 35, 1083–1092. Hege, A. C. G., & Dodson, C. S. (2004). Why distinctive information reduces false memories: Evidence for both impoverished relational encoding and distinctiveness heuristic accounts. Journal of Experimental Psychology: Learning, Memory, & Cognition, 30, 787–795. Hopkins, R. H., & Edwards, R. E. (1972). Pronunciation effects in recognition memory. Journal of Verbal Learning and Verbal Behavior, 11, 534–537. Howe, M. L. (2006). Developmental invariance in distinctiveness effects in memory. Developmental Psychology, 42, 1193–1205. Hunt, R. R. (2003). Two contributions of distinctive processing to accurate memory. Journal of Memory and Language, 48, 811–825. Hunt, R. R. (2013). Precision in memory through distinctive processing. Current Directions in Psychological Science, 22, 10–15. Israel, L., & Schacter, D. L. (1997). Pictorial encoding reduces false recognition of semantic associates. Psychonomic Bulletin and Review, 4, 577–581. Kellogg, R. T. (2001). Presentation modality and mode of recall in verbal false memory. Journal of Experimental Psychology: Learning, Memory, & Cognition, 27, 913–919. Lloyd, M. E. (2007). Metamemorial influences in recognition memory: Pictorial encoding reduces conjunction errors. Memory & Cognition, 35, 1067–1073. Ly, A., Raj, R., Etz, A., Marsman, M., Quentin, F., Gronau, Q. F., et al. (2018). Bayesian reanalyses from summary statistics: A guide for academic consumers. Advances in Methods and Practices in Psychological Science, 1 http://dx.doi.org/10.1177/ 2515245918779348 MacLeod, C. M., Gopie, N., Hourihan, K. L., Neary, K. R., & Ozubko, J. D. (2010). The production effect: Delineation of a phenomenon. Journal of Experimental Psychology: Learning, Memory, and Cognition, 36, 671–685. McDermott, K. B., & Roediger, H. L. (1998). Attempting to avoid illusory memories: Robust false recognition of associates persists under conditions of explicit warnings and immediate testing. Journal of Memory & Language, 39, 508–520. Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 3, 353–383. Olszewska, J., & Ulatowska, J. (2013). Encoding strategy affects false recall and recognition: Evidence from categorical study material. Advances in Cognitive Psychology, 9(1), 44–52. Paivio, A. (1971). Imagery and verbal processes. New York: Holt, Rinehart, and Winston. Paivio, A. (1986). Mental representations: A dual coding approach. Oxford: Oxford University Press. Paivio, A., Clark, J. M., Digdon, N., & Bons, T. (1989). Referential processing: Reciprocity and correlates of naming and imaging. Memory & Cognition, 17, 163–174. Penney, C. J. (1989). Modality effect and the structure of short-term verbal memory. Memory & Cognition, 17(4), 398–422. Roediger, H. L., & McDermott, K. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology, 21, 803–814. Russel, W. A., & Jenkins, J. J. (1954). The complete Minnesota norms for responses to 100 words from the Kent-Rosanoff Word Association Test. (Tech. Rep. No. 11, Contract N8 ONR 66216, Office of Naval Research). Minneapolis: University of Minnesota. Schacter, D. L., Cendan, D. L., Dodson, C. S., & Clifford, E. R. (2001). Retrieval conditions and false recognition: Testing the distinctiveness heuristic. Psychonomic Bulletin & Review, 8, 827–833. Smith, R. E., & Hunt, R. R. (1998). Presentation modality affects false memory. Psychonomic Bulletin & Review, 5, 710–715. Strack, F., & Bless, H. (1994). Memory for nonoccurrences: Metacognitive and presuppositional strategies. Journal of Memory and Language, 33, 203–217. Thapar, A., & McDermott, K. B. (2001). False recall and false recognition induced by presentation of associated words: Effects of retention interval and levels of processing. Memory & Cognition, 29, 424–432. Westerberg, C. E., & Marsolek, C. J. (2006). Do instructional warnings reduce false recognition? Applied Cognitive Psychology, 20, 97–114.