Nonverbal conjunction errors in recognition memory: Support for familiarity but not for feature bundling

Journal of Memory and Language 55 (2006) 138–155

Journal of Memory and Language www.elsevier.com/locate/jml

Nonverbal conjunction errors in recognition memory: Support for familiarity but not for feature bundling q Todd C. Jones b

a,*

, James C. Bartlett b, Kimberley A. Wade

c

a School of Psychology, P.O. Box 600, Victoria University of Wellington, Wellington, New Zealand School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75083-0688, USA c Department of Psychology, University of Warwick, Coventry CV4 7AL, UK

Received 3 February 2005; revision received 10 January 2006 Available online 9 March 2006

Abstract Conjunction errors occur when participants incorrectly identify as ‘‘old’’ novel test stimuli created by recombining parts of two study stimuli (parent items). Prior studies have reported that the conjunction error rate is higher when parent items are studied together than when they are studied apart (a parent proximity effect). In several experiments we attempted to obtain parent proximity effects with naturalistic faces or pairs of symbol strings. We also varied the type of facial conjunction (Experiments 1, 3A–3C), the presentation rate during study (Experiment 5), and the study list length across experiments (long lists in Experiments 1, 3A, 3B, and 3C; short lists in Experiments 2, 4, and 5). Conjunction effects, but not parent proximity effects, occurred in each experiment. The results are consistent with familiarity-based explanations of the conjunction effect but fail to support a feature bundling hypothesis.  2006 Elsevier Inc. All rights reserved. Keywords: Memory; Recognition memory; Face memory; Conjunction errors; Conjunction effect; Familiarity; Features; Configurations; Parent proximity effects q

We thank M.C. Jones for providing one of his university yearbooks for the photographs and the University of Iowa Alumni Association for its interest and kind support. We thank Kirsty Novis, Kathryn Taylor, Rebecca Piatek, Stephanie Sharmon, Shaun Hayward, Samantha Cox, K.C. Owen, and Katherine Price for their help with data collection. We also thank Stephanie Sharmon for her help in tidying up and formatting one of the stimulus sets and Kathryn Taylor and Shelley Ford for their help editing an early draft of the manuscript. Finally, we thank Sharon Hannigan for verification of the time parameters for the experiments in Reinitz and Hannigan (2001). The results of Experiments 1–5 were reported at the 6th Meeting of the Society for Applied Research on Memory and Cognition (SARMAC), Wellington, New Zealand, Janurary 2005. The research was supported by grants awarded to the first author from the School of Psychology and the Faculty of Science, Victoria University of Wellington. * Corresponding author. E-mail address: [email protected] (T.C. Jones).

An approach to learn how memory functions is to consider how memory errors occur. A type of error that has attracted recent interest in recognition memory is a conjunction error—false identification of new stimuli composed of components from two stimuli (parent items) studied earlier. For example, following the presentation of pardon and vodka, the lure parka could be incorrectly identified as ‘‘old’’ (Underwood & Zimmerman, 1973). A related error, termed a feature error, is an incorrect ‘‘old’’ response given to a stimulus containing one previously studied component and one entirely new component (e.g., false ‘‘old’’ response for parka after either studying pardon or vodka, but not both; Jones & Jacoby, 2001; Kroll, Knight, Metcalfe, Wolf, & Tulving, 1996; Reinitz, Lammers, & Cochran, 1992;

0749-596X/$ - see front matter  2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jml.2006.01.002

T.C. Jones et al. / Journal of Memory and Language 55 (2006) 138–155

Rubin, Van Petten, Glisky, & Newberg, 1999). The generalization of conjunction effects is impressive, as these effects have been found with a variety of materials: syllable combinations (Underwood & Zimmerman, 1973), compound words (Ghatala, Levin, Bell, Truman, & Lodico, 1978; Underwood, Kapelak, & Malmi, 1976), two-word phrases (e.g., last week; Underwood et al., 1976), abstract figures (Kroll et al., 1996), cartoon-type faces, (Kroll et al., 1996), identikit face drawings (Reinitz et al., 1992), and face photographs (Searcy, Bartlett, & Memon, 1999). The present experiments used nonverbal stimuli with a particular focus on naturalistic faces. There is considerable agreement that a theory incorporating familiarity as a process provides a good explanation of feature and conjunction errors (Bartlett, Searcy, & Abdi, 2003; Jones, 2005; Jones & Atchley, 2002; Jones & Jacoby, 2001; Lampinen, Odegard, & Neuschatz, 2004; Reinitz & Hannigan, 2001, 2004; Rubin et al., 1999; Searcy et al., 1999; though see Reinitz et al., 1992). Familiarity also has been argued to underlie conjunction errors for face photographs (Bartlett et al., 2003) and word stimuli (e.g., Jones & Atchley, 2002; Jones & Jacoby, 2001; Jones, Jacoby, & Gellis, 2001; Lampinen et al., 2004; Rubin et al., 1999). The present experiments address a basic challenge for familiarity-based theories of conjunction effects. Parent stimuli studied closely together, usually within a trial, have produced higher conjunction error rates than parent stimuli studied apart, usually between trials (Hannigan & Reinitz, 2000; Kroll et al., 1996; Reinitz & Hannigan, 2001, 2004; Underwood et al., 1976).1 This parent proximity effect has been obtained primarily when the study procedure involved simultaneous (A and B, C and D, E and F) or alternating (A, B, A, B; C, D, C, D; and E, F, E, F) presentation of pairs of face drawings within a trial (Hannigan & Reinitz, 2000; Reinitz & Hannigan, 2001). In these cases, conjunctions created from pairs presented within a trial (CD) have produced higher error rates than conjunctions created from pairs presented in separate trials (AF). However, there is an apparent boundary for the effect with face drawings. A sequential presentation procedure (A, B; C, D; and E, F) has not produced a parent proximity effect (i.e., the error rate for conjunction CD is not greater than that for conjunction AF; Bartlett & Searcy, 1998; Hannigan & Reinitz, 2000; Reinitz & Hannigan, 2001; also see, Busey & Tunnicliff, 1999, for similar results with mathematical averages of parent faces). 1 This manipulation of the distance or lag between parent stimuli (i.e., parent-parent lag) should not be confused with the distance or lag between the parents and the conjunction lure (i.e., parent-conjunction lag; e.g., Jones and Atchley, 2002, in press). To avoid any confusion regarding effects from different lag manipulations (parent-parent or parent-conjunction), we refer to the effects of a parent-parent lag manipulation as a parent proximity effect.

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For words, parent proximity effects have been produced with a simultaneous presentation procedure (Reinitz & Hannigan, 2004), but the effects have been obtained inconsistently with a sequential presentation procedure (see Kroll et al., 1996; Reinitz & Hannigan, 2004; Underwood et al., 1976). Hannigan and Reinitz (2000) and Reinitz and Hannigan (2001) noted that parent proximity effects could not be accommodated by earlier feature-based theory (Reinitz et al., 1992; Reinitz, Morrisey, & Demb, 1994; Reinitz, Verfaellie, & Milberg, 1996) or familiaritybased viewpoints of conjunction errors without some additional mechanism. In the feature-based theories, stimuli are obligatorily broken into constituents (features). Episodic memory representations are formed for these features stimuli, and an attention-demanding binding process allows the encoding of relations among features (i.e., that is, the features are put back together to form configurations). Reinitz et al. (1996) proposed that, if a configuration is not available in episodic memory, either due to an encoding failure or selective forgetting (though see Jones & Atchley, 2002; Jones & Jacoby, 2001), then separate feature representations are conjoined at retrieval, providing the illusion of earlier co-occurrence. This illusion prompts one to commit a conjunction error. (Feature errors are not accounted for in the theory because the illusion is based on conjoint retrieval of episodic representations.) To account for parent proximity effects, Reinitz and Hannigan (2001) proposed that an attentional mechanism (e.g., switching attention between two stimuli) leads to the binding of all of the features of those stimuli in memory (also see Reinitz & Hannigan, 2004). Because this construal of binding goes well beyond the misbinding of features across dimensions (e.g., letter and color information in perception experiments, e.g., Treisman & Schmidt, 1982), we describe this process as feature bundling. This process is argued to increase the difficulty of reconfiguring features properly during retrieval and to increase the likelihood of a conjunction error. Simultaneous and alternation presentation procedures have been argued to promote feature bundling, leading to parent proximity effects. In contrast, a sequential presentation procedure has been argued to encourage the segregation of features from separate stimuli. Thus a sequential presentation does not reliably lead to parent proximity effects. The parent proximity effect deserves further examination for at least three different reasons. First, the bundling account of the proximity effect appears to contradict the influential claim that face processing is based on configural information (spatial relations within faces, Bartlett & Searcy, 1998; Murray, Rhodes, & Schuchinsky, 2003; Murray, Yong, & Rhodes, 2000; Searcy & Bartlett, 1996) or holistic representations that are not parsed in terms of features (Farah, Wilson, Drain,

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& Tanaka, 1998; Tanakah & Farah, 1993, 2003). While configural information and holistic representations have been variously defined (cf. Bartlett et al., 2003; Peterson & Rhodes, 2003), all variations of these ideas appear opposed to the idea that people would bind together features of two different faces (i.e., the mouth of Face A with the eyes of Face B) just because they are studied together. Second, as already mentioned, it challenges the hypothesis that familiarity in the absence of recollection is the sole basis for conjunction false alarms. Third, the range of conditions in which a proximity effect has been obtained is relatively narrow. The need for other established theories, particularly those for naturalistic faces, to account for the parent proximity effect seems uncertain until the effect is shown to generalize to more natural stimulus sets and a wider range of procedures. In the present experiments, we attempted to produce a parent proximity effect primarily with photographs of naturalistic faces, and we employed two types of conjunction faces to test the generality of our findings. To anticipate, despite considerable effort, we did not find a parent proximity effect in any of our experiments with naturalistic faces (Experiments 1–5) or in an experiment with arguably less configural stimuli (symbol sets; Experiment 6).

types of conjunctions was given afterward. The conjunctions were formed from either the features of parents presented within a study trial (within-trial conjunction) or the features of parents presented in separate trials (between-trial conjunction). There were minor procedural differences between our study and theirs, and we note these differences in the Results and discussion section. Method Participants In this experiment, as well as all those that follow, the participants were Victoria University of Wellington undergraduates who participated in return for credit toward an introductory psychology course requirement. In this experiment, as well as in the rest of the experiments we report, a basic criterion for inclusion in the data set was included to make sure that our participants were at least minimally motivated. The criterion was that old-new discrimination had to be greater than zero (i.e., hit rate—new false alarm rate >0). Only a few participants demonstrated performance at chance or below, and aside from switching keys designated for old and new judgments, these participants were confined to the experiments with longer lists. Forty-eight students participated in this first experiment.

Experiment 1 A parent proximity effect on conjunction error rates has been obtained several times with a simultaneous presentation procedure using face drawings (Hannigan & Reinitz, 2000; Reinitz & Hannigan, 2001). To establish the generality of the effect and to provide a further test of the feature bundling hypothesis, the stimuli in the series of experiments below were grey-scale photographs of males obtained from a University of Iowa yearbook, The Hawkeye (1963). Two sets of example parents (original photos) and the different conjunction faces constructed from them are shown in Fig. 1. For one type of conjunction, the inner configuration of features was intact (eyes, eye brows, nose, and mouth of one face recombined with the forehead, cheeks, jaw, chin, hair, and ears from another face; e.g., Searcy et al., 1999). For a second type of conjunction, the inner configuration was disrupted (eyes, eyebrows, and mouth from one face recombined with the nose, forehead, cheeks, jaw, chin, hair, and ears from another face). This latter type of conjunction is comparable to that used by Reinitz and Hannigan (2001) for their face drawings. We adapted the basic aspects of the simultaneous presentation procedure used in Reinitz and Hannigan’s (2001) Experiment 3. As in their experiment, pairs of faces were studied simultaneously for 16 s, and a recognition test containing old faces, new faces, and two

Stimuli and apparatus The stimuli for all of the experiments reported in this paper were developed by the first and the third author. Because the stimuli have not been described elsewhere, we describe them in detail. The stimuli were bitmap files of grey-scale photographs of male faces of European descent, none of whom wore eye glasses or had facial hair. All of the stimuli were obtained from The Hawkeye (1963). Males were chosen exclusively because of the greater conformity in hair style (primarily short hair). The photographs were all from the top of the torso (cutting across or just below the shoulders). The pose was either directly facing the camera or with the head slightly angled to the left or to the right. (For most photographs, both ears of a subject were visible.) All subjects in the photographs selected wore dark sport coats, white shirts, and dark neckties. Photographs were scanned to form a computer file. Adobe Photoshop was used for all editing of the photographs and to create conjunction stimuli. A uniform size of the images was established such that each image file (a bitmap file) appeared as a rectangle 10.8 cm in height and 7.9 cm in width on the computer screen. The photographs were cropped so that shoulders (and body below the shoulders) did not appear. If the publishing or photographic quality was compromised (e.g., extraneous dots appeared on the image), the images were improved by eliminating some undesirable marks.

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Fig. 1. Two example sets of original photographs (top 2) and the constructed faces (bottom 4) created from them. The two constructed faces (conjunctions) on the left have intact inner configurations; the two constructed faces (conjunctions) on the right have disrupted inner configurations.

For the construction of conjunction faces, photographs of individuals with similar poses and, where possible, somewhat similar appearance, were put into pairs. These pairs were used to construct two types of conjunctions, intact-inner-configuration conjunctions, and disruptedinner-configuration conjunctions. The intact-inner-configuration conjunctions were similar to those used by Searcy et al. (1999). The inner features (eyes, eyebrows, nose, and mouth) and outer features (forehead, hair, ears, cheeks, jaw, and chin) from a pair of faces were combined to create two conjunction faces (intact-inner-configuration set). The

inner features were cut individually from an original (a parent face) and pasted on the other face in the pair. The lines surrounding the inner features from the cutand-paste approach were carefully blended with the immediately surrounding area on a face so that the conjunction stimuli would not appear to have been doctored. An attempt was made to keep this blending process at a minimum. The disrupted-inner-configuration conjunctions were created in the same way, except the outer features and the nose of one original face were combined with the eyes, eyebrows, and mouth of the other original face.

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For Experiment 1, 252 faces were used: 80 originals, 160 constructions, and 12 fillers. For 80 of the constructions, the inner configuration of features was kept intact (Set A), but for the other 80 constructions, the inner configuration of features was disrupted (Set B). The 80 original faces were common to both sets. A given participant was assigned to either Set A or Set B. For each set, 40 pairs of constructed faces came from 40 pairs of original faces; thus conjunction items on the test could based on studying originals and testing constructions or studying constructions and testing originals. In all but the final experiment reported in this paper, the faces on the test were the constructions. In the present experiment, across participants, all of the 80 original faces were presented in the study phase, serving as parent faces for the conjunctions. The 12 filler faces were used for buffer trials. All of the experiments in the series used E-prime software (Schneider, Eschman, & Zuccolotto, 2002a, 2002b). Design and procedure The design employed a single within-participant factor (study condition: old, within-trial conjunction, between-trial conjunction, and new) and a single between-participant factor (stimulus set: intact inner configuration, disrupted inner configuration). Forty pairs of faces were divided into four lists of 10 pairs (20 faces in each set), and each list was assigned to a study condition. Each list, and hence each test face, occurred in each study condition equally often across participants. Throughout the experiment, instructions to participants appeared on the computer screen and an experimenter read these instructions aloud. For the study phase, participants were told to study the faces in preparation for a later memory test. There were 36 study trials, with a pair of faces shown on each trial. The first and last three study trials were used as primacy and recency buffers. On each study trial, a pair of face photographs appeared side by side in the center of a computer screen with a black background for a duration of 16 s. (This duration was used by Reinitz & Hannigan, 2001.) The distance between the two images was 1.9 cm. The intertrial interval (ITI) was 1 s. The faces in a study trial were either parent faces (originals) that would be used to later produce the conjunction test faces (con-

structed faces) or constructed faces that would appear again on the test as old faces. The order of the study conditions in the study list was held constant. Two trials (one in the old condition, one in the within-conjunction condition) always intervened the faces to be conjoined for the between-trial conjunctions. An old-new recognition test was given immediately following the study phase. There were 80 test trials and the test was functionally self-paced. The faces presented on the test were always those that were constructed (not the originals). Therefore, any strategy to recognize faces based on appearance (altered or unaltered) would be fruitless. A single pseudorandom order of the test faces was used for every participant. The order ensured that the different test conditions were evenly distributed. Across the two groups (i.e., stimulus sets), the order of the test faces was matched so that the pairs of faces (two faces with intact-inner configuration, two faces with disrupted-inner configurations) created from a given pair of originals occurred in the same test positions. On each test trial, a ready signal (a plus sign) appeared for 1 s in the center of the computer screen. A single face photograph then appeared for an old-new judgment, and a judgment was entered by pressing J (old) or F (new) on the keyboard. The maximum time allotted for a response was 15 s. After a recognition judgment was entered, the next trial began after an ITI of 1 s. Results and discussion The data appear in Table 1 as a function of stimulus set and condition. For both stimulus sets, the probability of an old response increased from new faces to conjunction faces to old faces. However, there was no evidence of a parent proximity effect. A Repeated Measures ANOVA on the four study conditions with stimulus set (intact inner configuration, disrupted inner configuration) as a between-participant factor gave a significant effect of study condition [F (3, 138) = 105.74, MSE = 0.01], but neither the main effect of stimulus set [F (1, 46) = 0.00, MSE = 0.05] nor the Stimulus set · Study condition interaction [F (3, 138) = 1.14, MSE = 0.01] was significant. Planned comparisons showed that the conjunction error rate (collapsed across the within-between manipulation) was significantly lower than the hit rate [F (1, 47) = 108.37, MSE = 0.02] but sig-

Table 1 Proportion of ‘‘Old’’ responses for the simultaneous presentation procedure by experiment, stimulus set, and study condition Exp.

Stimulus set

Old

W-trial Conj.

B-trial Conj.

New

1 1 2

Intact IC Disrupted IC Intact IC

.71 .66 .86

.46 .47 .58

.45 .45 .58

.25 .29 .20

Note. Exp., Experiment; W-trial Conj., within-trial conjunction; B-trial Conj., between-trial conjunction; and IC, Inner configuration.

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nificantly higher than the false alarm rate for new faces [F (1, 47) = 112.17, MSE = 0.02 ]. A final planned comparison showed that mean within-trial and between-trial conjunction error rates were not significantly different, F (1, 47) = 0.54, MSE = 0.03. In short, the experiment reproduced the basic conjunction effect but failed to produce a higher error rate for the within-trial relative to the between-trial conjunction condition (i.e., it failed to produce a parent proximity effect) for two different types of conjunctions.

Experiment 2 The most basic aspects of the Experiment 1 procedure—simultaneous presentation of faces and study duration—were the same as those used by Reinitz and Hannigan (2001). However, there were still several differences between the two procedures. Reinitz and Hannigan presented their pairs of face drawings one above the other with slide projectors, whereas we presented the face photographs side by side on a computer screen. They used five study trials in total with the first and fifth trials designated primacy and recency buffer trials. By comparison, we used 36 study trials with the first three and last three trials designated as buffer trials. In their study, between-trial conjunctions were formed by combining elements from the second and fourth trials. Thus, one trial intervened the features that were combined for the between-trial condition. In our experiment, two trials always intervened the faces in the between-trial condition, which was equivalent to Reinitz and Hannigan’s (2001) far-condition in their Experiment 1 (also see Hannigan & Reinitz, 2000). The ITI was 10 s in their experiment but 1 s in our experiment. Their test was given after a 15-min retention interval, whereas our test was given immediately after the study phase. On the recognition test, they used two stimuli per condition (old, within-trial conjunction, between-trial conjunction, new), but we used 20 stimuli per condition. For their recognition test procedure, each face was shown for 6 s with an ITI of 4 s, and subjects circled ‘‘old’’ or ‘‘new’’ on a response sheet. In contrast, our recognition test was conducted on the computer and was functionally self-paced (participants had up to 15 s to respond). While any of these differences might prove to be important, no existing theory or empirical generalization would have predicted that proximity effects would hinge upon them. That is, there is nothing about the feature bundling hypothesis that indicates any of these differences would produce different results. Aside from the use of naturalistic faces instead of faces drawings, perhaps the most dramatic difference between our study and Reinitz and Hannigan’s (2001) is that we used many more stimuli in the study

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and test phases. For Experiment 2, we shortened the study list from 36 trials (72 faces) to 12 trials (24 faces), and our test contained 4 faces per condition. Feature bundling is proposed to reduce the functional length of a study list (Reinitz & Hannigan, 2001), but the mechanisms of feature bundling have not been proposed to be sensitive to list length itself. Nevertheless, the failure to reproduce Reinitz and Hannigan’s (2001) findings raised the possibility that proximity effects depend on short study lists. Experiment 2 addressed this possibility with a relatively small set of faces that contained intact inner configurations in the conjunction faces. One expectation was that the shortenting of the list length would produce a higher old-new discrimination relative to that obtained in Experiment 1. Whether the conjunction effect would change relative to Experiment 1 was of greater interest than an increase in old-new discrimination, though we save more thorough discussion of conjunction effect changes for the General discussion. Method Participants Forty-eight students participated. Materials A subset of faces from the intact-inner-configuration set from Experiment 1 were used. Across participants, 16 original photographs and 16 constructions appeared in study phase, and 12 faces were always used for buffer trials. Sixteen faces, all constructions, appeared on the test. Design and procedure There was a single within-participant factor, study condition (old, within-trial conjunction, between-trial conjunction, and new). The study and test instructions were the same as those in the Experiment 1. There were 12 study trials, 6 of which contained elements of faces for the later test. Two trials contained two faces that were later presented in the same form for the old condition (four total faces), two trials each contained a pair of faces that were recombined to form two within-trial conjunction faces on the later test (four total faces), and two trials each contained a pair of faces that were recombined across trials to form two sets of two between-trial conjunction faces (four total faces). The first three and final three trials were primacy and recency buffers. The timing of the trials in the study and test phases were also the same as in Experiment 1. A retention interval of about 24 min, during which a lexical decision task was given, intervened the study and the test phase. On the test, there were 16 trials, with 4 test items in each condition (old, within-trial conjunction, between-trial conjunction, new).

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Results and discussion The data are shown in Table 1. The pattern of ‘‘old’’ response rates was the same as in Experiment 1 (old > conjunction > new), but no parent proximity effect was obtained. Planned comparisons demonstrated that the combined conjunction error rate was significantly higher than the baseline error rate, F (1, 47) = 85.31, MSE = 0.08, but significantly lower than the hit rate, F (1, 47) = 56.44, MSE = 0.07. The two conjunction error rates were not significantly different, F (1, 47) = 0.00, MSE = 0.11. As expected, the hit rate was high and the baseline false alarm rate was low relative to Experiment 1. Conjunction error rates were higher in Experiment 2 compared to Experiment 1. This pattern could be described as an ironic effect of list length, where shorter lists increase old-new discrimination, which is good, but increase conjunction-new discrimination, which is undesirable. In terms of the conjunction errors, the shortened list length of Experiment 2 probably served to increase the impact of featural information or familiarity in face recognition memory. Despite this suggestion that featural information may have been more important in Experiment 2 than in Experiment 1, there was no evidence that features of faces studied together were bound together.

Experiments 3A, 3B, and 3C Parent proximity effects were not obtained for a simultaneous presentation procedure in our first two experiments. These failures were not due to a lack of effort. In Experiment 1, there were 960 observations per condition. In Experiment 2, the number of observations per condition was 192, which is comparable to the numbers of observations in Reinitz and Hannigan’s (2001) Experiment 1 (216) and Experiment 3 (120). The rationale for the next three experiments was that the simultaneous presentation procedure in Experiments 1 and 2 might have been inadequate to induce our participants to hold pairs of faces simultaneously in working memory (cf. Reinitz & Hannigan, 2004). It is possible, for example, that when our participants were presented with a pair of faces, they simply looked first at one face and then at the other, just as if they were presented sequentially. While effects obtained with the simultaneous procedure have been consistent (Hannigan & Reinitz, 2000 and Reinitz & Hannigan, 2001), the largest parent proximity effect found by Reinitz and Hannigan (2001) was obtained with an alternating (ABAB) procedure (in their Experiment 4). This observation suggests the hypothesis that the alternating procedure might be more effective in inducing simultaneous processing of both faces of a pair. To address this possibility, we conducted three

experiments that attempted to produce the proximity effect with a stimulus alternation procedure. Further, in one of these experiments, Experiment 3C, we attempted to enforce simultaneous processing of both faces of a pair by having participants judge which face of each pair was the more attractive. We note finally that while Experiment 3A employed the intact-inner-configuration conjunctions used in Experiment 2, Experiment 3B re-introduced the disrupted-inner-configuration conjunctions used in Experiment 1. Experiment 3C employed both types of conjunctions, making stimulus set a between-groups variable (as in Experiment 1). As in Experiment 1, the goal was to ensure that the effects we obtained would generalize across at least two types of conjunctions. Method Participants There were 20 participants in Experiment 3A, 20 participants in Experiment 3B, and 40 participants in Experiment 3C. Materials The stimuli from Experiment 1 were used. In addition to the stimuli from Experiment 1, 10 pairs of original faces (20 total) were used to make 20 pairs of constructed faces (40 total—20 with an intact inner configuration, 20 with a disrupted inner configurations), and another 30 pairs of original faces (60 total) were used to make 60 constructed faces (30 with an intact inner configuration, 30 with a disrupted inner configuration; additional constructions for these 30 pairs of originals looked too peculiar to be used). Thus for some of the additional stimuli, either the originals or the constructions could be presented in the study phase with the other face type (constructed or original) presented on the test as conjunctions. However, for the 30 pairs of originals with just one viable construction per set, a conjunction test item could only be produced by presenting the originals in the study phase and the constructed face on the test. As in Experiment 1, only constructed faces appeared on the recognition test. In total, there were 130 stimuli constructed for each stimulus set (inner configuration intact or disrupted), plus 140 original faces. Twenty-four more faces were used as buffer or filler stimuli. Design and procedure The stimulus set with intact inner configurations was used in Experiments 3A and 3C, and the stimulus set with disrupted inner configurations was used in Experiment 3B and 3C. For Experiments 3A and 3B, there was a single within-participant factor, study condition (old, within-trial conjunction, between-trial conjunction, and new). Experiment 3C manipulated the stimulus set directly by including it as a between-subjects factor.

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Minor changes from Experiments 1 and 2 included an increase in the proportion of faces with studied components on the test and an equal number of old and conjunction items. Eighty percent of the test faces contained studied elements; 40% of the faces were old and 40% of the faces were conjunctions. Five lists were used instead of four (two for old faces, two for conjunction faces, and one for new faces). There were 26 critical items in each list. Ten sets of two constructed faces (20 faces) came from 10 original pairs. Another six constructed faces came from six sets of original pairs. (Again, the other constructed face for each of these six sets appeared too peculiar to be used.) The five lists were rotated through the different study conditions. Normative data on attractiveness, distinctiveness, and estimated age were used to match (roughly) the study lists in terms of the average ratings for each conjunction mini-set (all of the faces created from an original pair). The study instructions were the same as in Experiments 1 and 2. There were 68 study trials. The first two and the final two trials were buffer trials to protect against primacy and recency effects. On each trial two faces were presented twice in alternation (ABAB). The order of the presentation (ABAB vs. BABA) was counterbalanced across participants. A single test order based on study condition was used. Stimuli from the relevant list were then called into the appropriate slots of the study list. As already noted, some original pairs of faces yielded one conjunction lure (instead of two) for each stimulus set. When the originals were presented in the study phase as a between-trial conjunction condition, a filler face was presented with each parent face. The duration of each face presentation was 4 s. Three 500-ms intervals of blank screen separated the presentation of the two faces. For Experiment 3C, after the two faces had been presented (twice), participants indicated which of the two faces was better looking (more attractive) by pressing 1 or 2 on the number pad (1 for the first face of the pair, 2 for the second face or the pair). The time allowed for the attractiveness judgment was 1.5 s. If a judgment was not entered within the time allotment, the program continued. The ITI was 1 s. The test instructions and test procedure were the same as in Experiments 1 and 2. There were 132 test tri-

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als. The only difference was that the first two trials of the test were faces presented in buffer trials of the study phase. These two trials were not scored. Results and discussion The data for Experiments 3A, 3B, and 3C appear in Table 2. The pattern of ‘‘old’’ responses, from highest to lowest probability, followed the pattern of old, conjunction, new, and this same pattern occurred for both stimulus sets. Overall, the within-trial and between-trial conjunction error rates were similar, disconfirming the prediction of more conjunction error in the within-trial condition. In fact, the within-trial error rate was a bit higher than the between-trial conjunction error rate in Experiment 3A. Planned comparisons on the hit rate, conjunction error rates, and baseline error rate (for new faces) showed that the hit rate was higher than the overall conjunction error rate [Experiment 3A, F (1, 19) = 69.65, MSE = 0.01; Experiment 3B, F (1, 19) = 44.31, MSE = 0.02; Experiment 3C, F (1, 39) = 103.95, MSE = 0.02]. Also, the conjunction error rate was significantly higher than the baseline error rate [Experiment 3A, F (1, 19) = 22.84, MSE = 0.01; Experiment 3B, F (1, 19) = 23.95, MSE = 0.01; F (1, 39) = 23.16, MSE = 0.01]. Finally, a (reverse) parent proximity effect was obtained for Experiment 3A [F (1, 19) = 7.63, MSE = 0.01], but no effect occurred for Experiment 3B [F (1, 19) = 0.33, MSE = 0.02] or Experiment 3C [F (1, 39) = 0.45, MSE = 0.02]. For Experiment 3C a Repeated Measures ANOVA on the four study conditions with stimulus set as a between-subject factor showed that there was no effect of stimulus set or Stimulus set · Condition interaction, Fs < 0.25. In Experiment 3A, the within-trial conjunction error rate was significantly lower than the between-trial conjunction error rate. Thus, the proximity effect was in the direction opposite to that predicted by the feature bundling hypothesis. However, this small effect is dubious because it was not replicated with the same items in Experiment 3C and did not occur in Experiment 3B or 3C with the other set of conjunctions (disrupted inner configuration). Again, no support was gained for the feature bundling hypothesis.

Table 2 Proportion of ‘‘Old’’ responses for the alternating presentation procedure by experiment, stimulus set, and study condition Exp.

Stimulus set

Old

W-trial Conj.

B-trial Conj.

New

3A 3B 3C 3C 4

Intact IC Disrupted IC Intact IC Disrupted IC Intact IC

.64 .65 .63 .65 .88

.40 .43 .40 .42 .62

.47 .42 .40 .39 .58

.31 .31 .30 .30 .17

Note. Exp., Experiment; W-trial Conj., within-trial conjunction; B-trial Conj., between-trial conjunction; and IC, inner configuration.

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Experiment 4 This experiment with naturalistic faces combined the stimulus alternation procedure of Experiments 3A–3C with the short study list of Experiment 2. Our thinking was simply that while neither of these conditions had produced a parent proximity effect, in combination they might to the trick. The additional experiment with a short list length also provided the opportunity to reproduce the relatively high hit rates and conjunction error rates and the relatively low new error rates that were obtained in Experiment 2.

Again, no evidence was obtained for a proximity effect. Relative to Experiments 3A, 3B, and 3C, the hit rate and conjunction error rates were elevated, whereas the baseline error rate was attenuated. The increases in old-new and conjunction-new discrimination from Experiments 3A and 3C to the present experiment match the ones observed from Experiment 1 to Experiment 2. Again, the increase in conjunction error rates, or conjunction-new discrimination, suggests that a shorter list somehow increases the impact of feature information (or familiarity) in face recognition memory. This point notwithstanding, again there was no evidence that features from different faces were bundled together.

Method Participants Forty-eight students participated. Materials The stimuli were the same ones from the intact inner configuration set used in Experiment 2. There were 16 critical items—four critical items per study condition— 32 originals, and 12 additional faces used as buffers in the study phase. Design and procedure A single within-participant factor, study condition (old, within-trial conjunction, between-trial conjunction, and new) was used. The numbers of study and test trials were the same as in Experiment 2. The timing of the study trials was the same as in Experiments 3A and 3B. Participants did not make an attractiveness judgment after each pair of faces was presented. The position of item types in the study list was counterbalanced across participants so that the studied conditions (old, within-trial conjunction, between-trial conjunction) appeared in each study list position (i.e., serial position) equally often across participants. The duration of the retention interval (about 25 min) and filler task were similar to those in Experiment 2. The test procedure was the same as in Experiment 2. Results and discussion The data appear in Table 2 by study condition. The probability of an ‘‘old’’ response increased from new faces to conjunction faces to old faces, but there was no evidence for a proximity effect. Planned contrasts showed that the hit rate was significantly higher than the overall conjunction error rate [F (1, 47) = 225.01, MSE = 0.04] and that the conjunction error rate was significantly higher than the baseline (new face) error rate, F (1, 47) = 82.17, MSE = 0.05. However, the error rates for the two conjunction conditions were not significantly different, F (1, 47) = 0.74, MSE = 0.11.

Experiment 5 A fifth experiment was conducted to address one additional procedural difference between our Experiments 1–4 and those of Hannigan and Reinitz (2000) and Reinitz and Hannigan (2001). Our ITI was comparatively short (2 s), whereas their ITI was unusually long (10 s). Their rationale for the long ITI was to help ensure that participants would group the two faces together. Because participants were also told they would see the stimuli presented together in pairs, we did not think this procedure to be necessary. Nevertheless, a long ITI could be critical to the effect, and we examined this possibility with our face photograph stimuli. The necessity of a long ITI would raise the possibilities that participants must hold on to the information in working memory for an extended period of time or that, after a pair or faces has been presented, several seconds are needed to consolidate the features of the faces into a feature bundle. A subsidiary purpose of this experiment was to test the possibility that conjunction errors in our prior studies reflected a strategy of basing recogniton decisions on a single feature (e.g., chin line or eye shape) or a particular combination of features (eye-mouth combination or chin line-hair combination).2 Obviously, such a strategy would preclude the appearance of proximity effects as the latter depend on encoding and retrieval of different features across pairs of a faces (chin line of one parent and the eye shape of the other parent). To address this possibility, the recognition test of Experiment 5 included faces comprising old and new parts (i.e., feature lures), and two types of feature lures were used (inner features old but outer features new and outer features old but inner features new).

2 We thank an anonymous reviewer for pointing out this possibility. We also note that feature lures were not included in any of Hannigan and Reinitz’s (2000) or Reinitz and Hannigan’s (2001) experiments.

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Method Participants Ninety-six students participated. Materials Only face photographs with inner configurations intact for the conjunctions were used. Two sets (A and B) of 6 pairs (12 total pairs; 24 total faces) were used. The stimuli in Set A showed a strong tendency in Experiments 3A, 3B, and 4 toward a parent proximity effect. The stimuli in Set B showed a strong tendency in those same experiments toward a reverse parent proximity effect. The sets were chosen in an attempt to bias the findings toward an effect, one way or the other. However, results did not differ for the two stimulus sets and so we have collapsed the data across stimulus set in the analyses below. Two pairs of faces were included as buffers during the study phase. Design There were two factors, ITI (short or long) and condition (old, within-trial conjunction, between trial conjunction, inner features old, outer features old, and new). ITI was manipulated between participants, but condition was manipulated within participants. Procedure The participants were instructed that faces would be presented in pairs, one face above the other, and that they should carefully study each face in the pair, dividing the time (16 s) equally between the two faces (e.g., Hannigan & Reinitz, 2000). Each participant saw six study trials with either stimulus Set A or stimulus Set B. The first and last study trials were buffers against primacy and recency effects, and the middle four study trials contained stimuli used to create five test conditions (old, within-trial conjunction, between trial conjunction, inner features old, and outer features old). The two study faces for the old test condition were presented in one study trial; the two parent faces for the within-trial conjunction condition were presented in one study trial and yielded two within-trial conjunctions on the test; the two parent faces for the between-trial conjunction condition were presented in separate trials and yielded two between-trial conjunctions one the test; the parent study faces corresponding to the feature test conditions were always paired with a face in the between-trial condition, and each face yielded two feature test stimuli (one with the inner features old, one with the outer features old). Finally, two new faces on the test had no features in common with faces seen at study. All of the faces in the recognition test were original face photographs (i.e., constructions only appeared as parent items at study). The six study conditions and items were rotated such that, across participants, the items in the test

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Table 3 Schematic of the study list design for Experiment 5 Study trial P#

1

2

3

4

5

6

1

2

3

4 Note. P#, participant number; B, buffer face; O, face used for the old condition; CJB, face used to produce between-trial conjunction lures; CJW, face used to produce within-trial conjunction lures; and F, face used to produce feature lures.

conditions corresponded to items presented in each of the four middle study positions (Table 3). For each study trial, two pairs of faces were presented simultaneously for 16 s. The ITI for one group of participants was 10 s; the ITI for a second group of participants was 2 s. The short and long ITI groups started the study phase at the same time but the short ITI group finished about 40 s before the long ITI group. There was a 12-min retention interval after the study phase. During the retention interval participants filled out an unrelated survey on political attitudes. For the test, all of the stimuli were original photographs. Each test face occurred in each condition equally often across participants. The participants were instructed to judge a face old only if it exactly matched a face presented in the study phase (e.g., Hannigan & Reinitz, 2000). No mention was made of the feature or conjunction lures. A single test order of items was used for all participants. Each test face was presented for up to 6 s. The ITI during the test was 1 s. Results and discussion The data for the two ITI groups appear by condition in Fig. 2. First, the data show the usual pattern of ‘‘old’’ judgments (old, .84 > conjunction, .53 > feature, and .34 > new, .12). A 2 (ITI) · 4 (Condition) ANOVA produced a main effect of condition, [F (3, 282) = 136.10, MSE = 0.07], and a Bonferroni adjustment for multiple comparisons showed that each of the four conditions was significantly different from the others. The overall conjunction error rate was significantly higher than the overall feature error rate the conjunction effect in this

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Proportion of "Old" Responses

1.0 0.9 Short ITI Long ITI

0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

Old

W-Conj. B-Conj.

O-Feat.

I-Feat.

New

Condition Fig. 2. Experiment 5: proportion of ‘‘old’’ responses by study condition and ITI group. W-Conj., within-trial conjunction; BConj., between-trial conjunction; O-Feat., outer features old; and I-Feat., inner features old. Error bars reflect the 95% confidence interval for each mean.

experiment, demonstrating that both inner and outer features influenced recognition judgments for the conjunction conditions. The long ITI group produced more hits and conjunction errors, but fewer new face errors, compared to the short ITI group. The main effect of ITI was not significant, F (1, 94) = 3.43, MSE = 0.07. The ITI · Condition interaction was significant, F (3, 282) = 3.43, MSE = 0.07. The false alarm for new faces was significantly lower for the long ITI group (.06) than the short ITI group (.17), F (1, 94) = 24.78, MSE = 0.05. An analysis of the data without the new faces did not produce an effect of ITI, F (1, 94) = 1.38, MSE = 0.08, but an analysis of the corrected scores (subtraction of the nonstudied baseline), showed that, overall, scores were higher for the long ITI group, F (1, 94) = 6.43, MSE = 0.27. Neither of these latter two analyses produced a Condition · ITI interaction. Of greatest relevance to the goals of this study, there was no evidence of a parent proximity effect for either ITI group. The means in Fig. 2 show that, overall, the conjunction false rate was higher than the feature false alarm rate. These data also suggest that, for the short ITI group, the outer-feature items evoked more false alarms than inner-feature items. A Repeated Measures ANOVA on the four corrected feature and conjunction scores (i.e., subtraction of the false alarm rate to new faces) with ITI as a between-participants factor showed that the effect of condition was significant, F (3, 282) = 8.92, MSE = 0.13, as was the effect of ITI, F (1, 94) = 5.66, MSE = 0.13. Although the data suggested an interaction based on the relatively high outer-feature conjunction error rate for the short ITI condition, the Condition · ITI interaction was not significant, F (3, 282) = 1.69, MSE = 0.13. For the effect of condition (collapsed across ITI), follow-up Bonferroni-adjusted comparisons confirmed that the between-trial conjunc-

tion and within-trial conjunction scores were not different from each other but were each higher than each of the feature scores, which were not different from each other. (The overall mean difference for the conjunction and feature conditions was 0.190 with a 95% confidence interval of 0.076.) Thus, although the conjunction scores were significantly above that for the feature scores, no parent proximity effect was obtained. Our primary question was whether proximity effects would differ for the two procedures (i.e., an interaction of conjunction scores and ITI procedure). Although the long ITI produced higher (corrected) hits and conjunction and feature error scores than the short ITI, there was no evidence for a parent proximity effect with either ITI. Despite the fact that the long ITI was the same as that used by Hannigan and Reinitz (2000) and Reinitz and Hannigan (2001), their parent proximity effect was not obtained. The main effect of ITI on corrected hit scores and conjunction and feature scores indicates that our manipulation was sufficiently strong to produce an effect, and this effect is of theoretical interest as well. Similar to the effects of shortening list length across our earlier experiments, slowing the presentation rate appears to have produced an ironic effect whereby hit scores increased at the cost of higher error scores. We return to this issue in the General discussion.

Experiment 6 In Experiments 1–5 (seven experiments in total) we failed to obtain a parent proximity effect, and hence, we found no evidence for the feature bundling hypothesis. One possible explanation for this unexpected outcome is that our materials—naturalistic faces—are strongly configural and/or holistic in character, such that their features are not encoded independently of each other. Without independent encoding of features, it may simply be impossible for the features of one stimulus to be bundled together with those of another. We note that Reinitz and Hannigan (2001) found proximity effects using face-drawing stimuli that may lack the strong configural and/or holistic character of naturalistic faces (see Leder, 1996, and the Introduction). Independent encoding of features may be more likely with face drawings than with naturalistic faces, and this characteristic may explain why Reinitz and Hannigan found proximity effects while we did not. With these considerations in mind, we attempted to obtain the parent proximity effect with different materials. Our question was whether the ‘‘features’’ of these loosely configural stimuli would be subject to bundling so that a parent proximity effect would (at last) be obtained. We used relatively simple nonverbal stimuli that were designed to allow independent encoding of their constituent features or parts. Each stimulus was a

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149

Fig. 3. Example stimuli for Experiment 6.

six element string composed of two different foreign language symbols (three copies of one symbol followed by three copies of the other, see Fig. 3). Based on the Gestalt laws of similarity, proximity, and discontinuity, we assumed that the elements of each stimulus would be grouped by symbol type, with the three copies of each symbol processed as a ‘‘feature.’’ Conjunction test probes were created by rearranging the ‘‘feature’’ on the left side of one stimulus pair with the ‘‘feature’’ on the right side of another pair (either within or across trials). To make our procedure more similar to Reinitz and Hannigan’s (2001, 2004) studies, we presented the stimulus pairs one above the other. Reinitz and Hannigan (2004) used up to six study trials for a study list, so and we presented the stimuli in three study lists of six trials.

the features of two different scripts (Japanese-Arabic, Greek lower case-Chinese, and Hebrew-Greek/Cyrrilic upper case) such that the symbols from a given script always occurred in the same position (left or right) within a pair. The symbols were presented in black on a white background. Additional pairs of symbol strings were used as parent stimuli (24) for the conjunction conditions and as primacy (6) and recency (6) buffers.

Method

Procedure We used three short lists of five study trials, and two pairs of symbol features were presented simultaneously on a trial (simultaneous presentation procedure). Only one set of symbol pairs (e.g., Japanese-Arabic) was seen in a study list, and the different sets of symbol pairs appeared equally often in the first, second, and third study list. We followed Reinitz and Hannigan’s (2001) procedure for the study list construction. The first and fifth trials of each study list were primacy and recency buffer trials, respectively, the second and fourth trials always contained the parent stimuli for later conjunction conditions, and the third trials always contained the pairs for the old condition. For the conjunction conditions, the

Participants Forty-eight students participated. Materials Japanese, Arabic, Chinese, Greek (upper and lower case), and Cyrrilic (upper case) symbols were selected from those available in Microsoft Word 2000. Each stimulus feature comprised three instances of a single symbol, and the font size and bold options were adjusted to make the symbols similar in size (height 1.6– 2.5 cm; width of a string of three symbols, 4.8– 7.6 cm). Twenty-four target pairs were created from

Design A single within-participant factor, study condition, was used. There were four levels of the factor: old, within-trial conjunction, between-trial conjunction, new. Each symbol string appeared in each condition equally often across participants.

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pairs in the second and fourth positions of a list were combined to produce one within-trial conjunction from both list positions (2 total) and two between-trial conjunctions across the two list positions. Participants were instructed to learn the symbols as left-right pairs for a later memory test. On each trial, two pairs of symbol features were presented, one above the other, for 16 s. The left and right members of a pair were separated by 1.28–2.54 cm, and the upper and lower pairs of a trial were separated by 7.5 cm. Because ITI did not turn out to be critical for a parent proximity effect to occur in Experiment 5, and wishing to minimize the factor of boredom, we returned to the ITI of 2 s. At the end of the first and second study lists, the participants pressed a key (at their own pace) to begin the next study list. The recognition test instructions were given immediately after the third study list. Participants were told to identify only exact copies of study stimuli as ‘‘old.’’ No mention was made of the conjunction lures. The items from the different study lists and for the different conditions were distributed throughout the test. Up to 10 s were given to enter a recognition judgment, and the ITI was 1 s.

1.0 0.9 0.8 0.7

P("Old")

150

0.6 0.5 0.4 0.3 0.2 0.1 0.0 Old

W-Trial Conj.

B-Trial Conj.

New

Condition Fig. 4. Experiment 6: proportion of ‘‘old’’ responses by study condition. Error bars reflect the 95% confidence interval for each mean.

hint of a parent proximity effect than did the face stimuli used in our prior studies. Thus, no evidence was found for the feature-bundling theory with either naturalistic faces or less configural symbol string pairs.

Results and discussion A small number of participants indicated that they were a bit familiar with a few of the symbols (Greek, Japanese, or Hebrew), but we considered this knowledge to be somewhat similar to being familiar with a nose as a nose, for example. The data from these more knowledgeable individuals closely resembled those of the others and so there was no evidence that amount of symbol knowledge produced any differences on the test. The same pattern of results was obtained across the different symbol scripts (Japanese-Arabic, Greek lower case-Chinese, and Hebrew-Greek/Cyrrilic upper case), and we therefore collapsed over script-type in computing the overall proportions of ‘‘old’’ responses that are shown in Fig. 4. As can be seen, accuracy was very good for old and new symbol pairs. A strong conjunction effect was obtained, but a parent proximity effect was conspicuously absent. Formal analyses verified these observations. Planned comparisons showed that the hit rate was higher than the conjunction error rate [F (1, 47) = 21.50, MSE = 0.05] and that the conjunction error rate was higher than the new pair error rate, F (1, 47) = 328.21, MSE = 0.04. The within-trial and between-trial conjunction conditions were not significantly different, F (1, 47) = 0.04, MSE = 0.06. We reasoned that the failures to obtain a parent proximity effect in our first six experiments could reflect our use of configural or holistic stimuli whose parts were not encoded independently of each other. The symbol pairs of the present experiment were designed to be only weakly configural, at best, yet they produced no more

General discussion Our primary goal was to test the hypothesis that the features of stimuli that are attended together can be bundled together in a memory representation. This feature bundling hypothesis has been supported with the appearance of parent proximity effects by using face drawings as stimuli. When pairs of face-drawings were presented simultaneously or in alternation within a study list, conjunctions of faces paired together at study evoked more false recognitions than conjunctions of faces from separate pairs. We wished to learn if this proximity effect extends to other stimuli, particularly naturalistic faces that—according to a good deal of research and theory—can be processed as configurations or wholes (e.g., Tanakah & Farah, 1993, 2003). None of our experiments with naturalistic faces produced a parent proximity effect, and one experiment (Experiment 3A) showed a significant effect in the opposite direction. The failure to obtain a parent proximity effect occurred with simultaneous (Experiments 1, 2, and 5) and stimulus alternation (Experiments, 3A, 3B, 3C, and 4) study procedures and with long (Experiments 1, 3A, 3B, and 3C) and short (Experiments 2, 4, and 5) study lists. Across the face experiments, the total numbers of conjunction errors were 1638 for the within-trial conjunction condition and 1631 for the between-trial conjunction condition (out of 3616 opportunities), yielding a 0.002 difference in the overall proportions of conjunction errors. Despite plenty of observations and

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opportunities to detect a higher error rate for within-trial compared to between-trial conjunctions, a parent proximity effect was not obtained, even when an extremely similar procedure (short study list with a 10-s ITI) to that of Reinitz and Hannigan (2001) was used in Experiment 5. Finally, in Experiment 6, we attempted to obtain a parent proximity effect with stimuli (pairs of symbol triplets) that we think are more likely to be encoded as features and less likely to be encoded as configurations or Gestalts. Again, our attempt failed. Therefore, the elusiveness of the effect is not confined to stimuli that are strongly configural. Though we have no reason to doubt the veracity of the parent proximity effects obtained with face drawings (Hannigan & Reinitz, 2000; Reinitz & Hannigan, 2001) there was no shred of evidence that the phenomenon generalizes to the conditions and materials used in the present studies. An additional goal of the present studies was to test the generality of our results across two types of conjunction. Moscovitch, Winocur, and Behrmann’s (1997) research with an agnosic patient points to the possibility that, while configural processing is important with faces, only those features in the inner facial region are processed as configurations. Thus, the functional components supporting face recognition might include aspects of the hair, chin, ears, etc., along with a unitary eyes/nose/mouth Gestalt. The idea that the internal features are processed as a unit implies that the conjunction effect and the proximity effect both might be stronger for conjunctions where the inner-Gestalt (e.g., our intact-inner-configuration conjunctions) is maintained than for those where the inner-Gestalt is destroyed (e.g., our disrupted-inner-configuration conjunctions; also see McKone and Peh, in press). Overall though, the present experiments do not support any reliable differences between the two types of conjunctions, suggesting that configural processing by normal individuals is not restricted to the inner facial region. Whether the faces are familiar, however, is likely crucial. Some research has shown that isolated inner configurations are more important than outer isolated features for familiar faces only (Ellis, Shepherd, & Davies, 1979; also see Young & Bruce’s, 1991, comments), so processing of an inner configuration as a unit (e.g., Moscovitch et al., 1997) may evolve as a face becomes familiar. Regarding the primary goal of this study, our observations show that parent proximity effects do not generalize across different types of stimuli as well as do conjunction effects. Our results suggest that there may be something special about Reinitz and Hannigan’s (2001) stimuli, or perhaps the combination of their face drawing stimuli with a narrow set of study parameters (i.e., a long ITI), that promotes parent proximity effects. Another possibility is that some characteristic of our face and symbol stimuli circumvents parent proximity

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effects. In either case, the present research has uncovered conditions in which a familiarity-based theory would appear sufficient to explain conjunction errors without any feature-bundling process. In cases where a parent proximity occurs, a straightforward familiarity explanation may not be sufficient. For this reason, it is important to determine what the latter cases are. Experiment 6 tested one idea, namely that our face photographs might be too strongly configural to be broken into features. However, our test of this strong configurality hypothesis with less configural stimuli (i.e., pairs of symbol strings) failed to find any support. Another possibility is that only more simple stimuli are like to produce a parent proximity effect. Because our face photographs are clearly more complex than Reinitz and Hannigan’s (2001) face drawings, the factor of complexity might explain why parent proximity effects were absent in our studies. Unfortunately, it is not clear how the complexity of the symbol stimuli in Experiment 6 compares to that of the face drawings or the more naturalistic faces used here. At an intuitive level, our symbol stimuli appear rather simple, in which case the lack of a proximity effects cannot be blamed on a high level of complexity. However, our intuitions on complexity for the symbols might not be valid, and we have no objective metric of stimulus complexity that applies across stimulus domains. Very recently, McKone and Peh (in press) obtained a parent proximity effect for naturalistic faces with Reinitz and Hannigan’s (2001) procedure, but McKone and Peh’s stimuli appear to support our suggestion regarding stimulus complexity. The naturalistic faces in their study were presented looking directly into the camera and within an oval window so that only the inner configuration of features (eye brows, eyes, nose, and mouth) was visible. (Interestingly, McKone and Peh eliminated hair information from their stimuli with the reasoning that hair information would promote feature processing, thus facilitating parent proximity effects.) By limiting the visible features of the faces to the very inner features with a head-on view only, they simplified their stimuli. Therefore, to date, parent proximity effects for face stimuli have been obtained only with relatively simple face stimuli. Our present research has concentrated on nonverbal materials, but in the broad view, there have been four explanations of parent proximity effects. For face stimuli, the idea is that feature bundling occurs during encoding and that features encoded into the same bundle are more likely to be conjointly retrieved (Reinitz & Hannigan, 2001). For word stimuli, three different suggestions have been made. First, the target item may come to mind during study (Underwood et al., 1976), leading to the possibility of a reality monitoring error during the test. Second, due to errant binding, the elements of separate word stimuli may be bound together inappropriately during encoding, especially by individuals with

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left hippocampal damage, to form an inaccurate memory representation (Kroll et al., 1996). Third, if two verbal stimuli are held in working memory simultaneously, then parent proximity effects are likely to occur (Reinitz & Hannigan, 2004). None of these ideas appear to be mutually exclusive. Underwood et al. target generation idea and Reinitz and Hannigan’s (2004) working memory suggestion seem roughly compatible but more likely to apply to word stimuli than to face stimuli. (We note that Reinitz & Hannigan, 2004, argued against the possibility of compound word target generation during study.) Also, holding information in working memory could be a precursor for effects from errant binding or feature bundling. What seems apparent is that, while parent proximity effects are intriguing, they are poorly understood. The fact that we repeatedly failed to obtain parent proximity effects should be helpful in understanding how and when they occur, at least with nonverbal stimuli. One possibility is that the amount of information in our relatively complex stimuli may have exceeded what could be held in working memory, meaning that feature bundling was compromised. The results from the present experiments fit with the proposal that familiarity provides a major basis for conjunction errors with faces (also see Bartlett et al., 2003; Searcy et al., 1999) and verbal stimuli (Jones and Atchley, 2002, in press; Jones & Jacoby, 2001; Lampinen et al., 2004; Rubin et al., 1999; also see Marsh, Hicks, & Davis, 2002). Familiarity-based theories have been preferred to feature-configuration theories by some researchers because they account for conjunction effects, as well as feature effects (Busey & Tunnicliff, 1999; Jones & Jacoby, 2001; Lampinen et al., 2004; Rubin et al., 1999). In addition, evidence indicates that (a) obligatory part-based processing to construct facial configurations, as appears to be suggested by Reinitz and colleagues (Reinitz & Hannigan, 2001; also see Reinitz et al., 1996) would be inefficient and (b) configurations, or holistic processing, can occur in the absence of partbased processing (McKone & Peh, in press). For dual-process approaches that incorporate familiarity, the proposal is that feature and conjunction errors are based on familiarity in the absence of recollection, and experiments with compound words have shown that participants can use a recollection (recall) process to reject conjunction lures (Jones, 2005; Jones and Atchley, 2002, in press; Lampinen et al., 2004; Odegard et al., in press; also see McDermott, Jones, Petersen, Lageman, & Roediger, 2000). Recollection-based rejection might sometimes occur with face stimuli, too, though we suspect that its role will prove limited, particularly when the faces are of unknown persons (as in the present studies). Given that all of the features of old and conjunction faces are similarly familiar, one should wonder why old and conjunction faces are reliably distinguished for upright faces. One possibility is that familiarity strength

is affected by how well the global configuration of a test face matches with representations in memory. Hence, while many conjunctions may be perceived as familiar because they match representations in memory with respect to constituent features, truly old faces will have, on average, higher familiarity because they match representations in memory with respect to configural information (e.g., McKone & Peh, in press; Yonelinas, Kroll, Dobbins, & Soltani, 1999). An alternative is that recollection contributes to the acceptance of old faces (e.g., Bartlett et al., 2003; Bastin & Van der Linden, 2003; Ma¨ntyla¨ & Cornoldi, 2002; Yonelinas et al., 1999; also see Vokey & Read, 1992) but not conjunction faces. Yonelinas et al.’s (1999) results with an receiveroperating-characteristic (ROC) approach suggest that old-conjunction discrimination for upright face drawings is based partly on differences in perceived familiarity, though recollection also appears to play a role in successful recognition of old faces. Future work should determine whether Yonelinas et al.’s (1999) findings extend to naturalistic faces. Another important task for future research is to bridge the currently capacious gap between general theories of memory and conceptions arising from research on face processing. Toward this aim, Bartlett et al. (2003) created and assessed an autoassociative-GAPS model based on prior work by Abdi, O’Toole, and colleagues (Abdi, 1988; Abdi, Valentin, & Edelman, 1999; O’Toole, Deffenbacher, Valentin, & Abdi, 1994; Valentin, Abdi, & O’Toole, 1994) in the context of Tulving’s (1983) general abstract processing system (GAPS). The autoassociative-GAPs model employs a pixel-based code that is holistic in the sense that it is not parsed in terms of identifiable facial features (i.e., eyes, noses, etc., see Farah et al., 1998; Tanakah & Farah, 1993, 2003). The model simulates recognition of real facial photographs (the same ones that human participants learn) using a familiarity-type process of computing the cosine—pixel by pixel—between a recognition cue and the ‘‘output image’’ produced by the model’s network in response to that cue. The model discriminates old faces from conjunctions (i.e., old/conjunction d 0 > 0) and shows the conjunction effect (conjunction/ new d 0 > 0). Further, it resembles human participants in producing ironic effects of study repetition (i.e., greater conjunction/new d’s when study list faces were presented three times as opposed to only once). A weakness of the model is that it overestimates the conjunction effect, a deficiency that Bartlett et al. (2003) attribute to the lack of a recollection process (other researchers have also posited that both recollection and familiarity support face recognition; see, e.g., Bastin & Van der Linden, 2003; Yonelinas et al., 1999; also see Vokey & Read, 1992). The model also does not include any clear emphasis on local configurations, so the relatively high conjunction effects could reflect a

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neglect for configurations. Despite this deficiency, the model is generally consistent with the idea that a familiarity-like process can work with a holistic (i.e., nonfeature-based) code (also see Yonelinas et al., 1999). This modelling approach provides another important means to understand face processing. The current results, particularly the list length and presentation rate effects that we note below, may provide an important impetus to further develop autoassociative-GAPS model. We now briefly turn to an unexpected but intriguing effect of study-list length on conjunction error rates across Experiments 1–5. Although we did not directly manipulate study list length in any one experiment, in line with many prior studies (e.g., Clark & Gronlund, 1996; Gillund & Shiffrin, 1984; Gronlund & Elam, 1994; Strong, 1912; Yonelinas, 2002), we found higher hit rates for old faces and lower false alarm rates for new faces when the study lists were short (Experiments 2, 4, and 5) than when they were long (Experiments 1 and 3). The unexpected finding is that short study lists led to higher conjunction error rates (for both within- and between-trial conditions).3 A similar effect was found for Experiment 5 where a slow presentation rate increased the hit rate slightly and clearly decreased the baseline false alarm rate. However, the feature and conjunction effects (i.e., feature and conjunction scores with the baseline error rate subtracted) were bigger for the short study lists. In sum, the conditions of shorter study lists and slower presentation produced the ironic effect of increasing feature and conjunction error rates (or effects). 3 The consistent differences based on study list length should be treated with appropriate caution because study list length was not directly manipulated in any one experiment and is confounded by items. However, potential item differences in the comparison of short lists to long lists were ruled out by comparing a subset of sixteen items used in both short and long study lists.. For two short list experiments (2 and 4) the mean ‘‘old’’ response rates (collapsed across experiments) were .87 (old) .60 (within-trial conjunction), .58 (between-trial conjunction), and .19 (new). For the long list Experiments 1, 3A, and 3C (collapsed across experiment), the mean ‘‘old’’ response rates were .72 (old), .48 (within-trial conjunction), .49 (betweentrial conjunction), and .24 (new). Further, treating items as participants, we conducted statistical analyses on the mean scores of these items for the different list lengths (short or long). List length was treated as a between-participants factor. The mean hit rate was significantly higher for the short study list experiments compared to that for the long study list experiments, F (1, 30) = 25.23, MSE = 0.01. A 2 (List length) · 2 (Condition: within-trial conjunction, between-trial conjunction) ANOVA on the conjunction error rates gave only a significant effect of list length, F (1, 30) = 5.02, MSE = 0.02, and a 2 · 2 ANOVA on the conjunction effects (i.e., conjunction error rate—new error rate) that used the same factors (i.e., list length and condition) also gave only a significant effect of list length, F (1, 30) = 26.33, MSE = 0.01. Thus, comparisons that used the same subset of items across these experiments support our conclusions.

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The ironic effect of study list length has implications for Reinitz and Hannigan’s (2001) explanation of parent proximity effects for face drawings. For a full discussion of their idea and results, we encourage the interested researcher to read their paper, as well as Reinitz and Hannigan’s (2004, p. 468) comment. The important point is that feature bundling accomplished during the simultaneous presentation of two faces was proposed to reduce the effective length of a study list (sort of like chunking, Miller, 1956), leading to a relatively low between-trial conjunction error rate. Thus, (functional) list length was argued to contribute to parent proximity effects. However, the ironic effect of list length across our experiments is opposite to the pattern suggested by Reinitz and Hannigan (2004). The implication is that functional list length may not have produced the relatively low between-trial conjunction error rate in their experiments; thus it may not have been a factor in their parent proximity effects. A plausible explanation of our ironic effects concentrates on memory for features. If feature memory is positively correlated with the perceived familiarity of conjunction and feature lures, and if false alarms for these items are based (largely) on perceived familiarity, it follows that any decrease in memory for features would decrease conjunction and feature errors. Ironic list length effects could be attributed to differences in the amount of interference from competing features, while ironic effects of presentation rate could be attributed to a reduction of encoding of features. It would appear that a single-process model based on familiarity could provide a good account of these results by making reasonable assumptions about list length and list strength. For example, presentation rate could operate in a manner consistent with study repetition (a list strength idea, e.g., Clark & Gronlund, 1996), and the autoassociative-GAPS model or global matching models (cf. Clark & Gronlund, 1996) could probably account for this finding.

Conclusion Parent proximity effects, which are the central phenomenon supporting feature bundling of face stimuli, have been obtained for some face stimuli (face drawings, Hannigan & Reinitz, 2000; Reinitz & Hannigan, 2001; inner configurations of naturalistic faces, McKone & Peh, in press), but the findings of the present experiments show that these effects do not readily extend to full naturalistic faces or symbol sets. The present results support a familiarity-based explanation of conjunction errors (e.g., a GAPS-ecphory perspective, Bartlett et al., 2003) but not feature bundling account. The take-home message is that parent proximity effects, even for simultaneous presentation conditions, do not appear

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to be as reliable as conjunction effects. Further research and theoretical advances are needed to better understand face recognition memory and parent proximity effects. At present, the best indicator for the appearance of parent proximity effects may be stimulus complexity, with parent proximity effects occurring for simple stimuli but not for complex stimuli.

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