Overshadowing Effect Research Articles

Does delay release the verbal overshadowing effect in child and adult eyewitnesses

• In spite of a large body of literature on the suggestibility of children testimony, only one study has examined whether descriptions also impaired children’s identification abilities in a single group of children (8-9 years old) and no evidence of VO was found (Memon & Rose, 2002). However, the method might not have been appropriate to observe this effect as the description and the control tasks were not completed immediately but after a 24h delay that has sometimes been associated to a release of the VO effect (e.g. Schooler & Englster-Schooler, 1990; Finger & Pezdek, 1999).

Red, Green, Blue, Red, Argh! A Missing Shift in Processing: The Stroop Task Does Not Affect Facial Recognition

The transfer-inappropriate processing shift is one explanation for the verbal overshadowing effect: a phenomenon that prevents accurate face recognition following a verbal description of that same face. Rather than examining a shift from configural to featural processing, this experiment investigated whether a shift from automatic to controlled processing could have similar deleterious effects on facial recognition. Automatic, and controlled, processing were induced using a computer-based Stroop task. Participants ( n = 288) processed the font colour, or word reading conditions of the Stroop task; afterwards, their facial recognition was tested. Even though the Stroop effect did occur, the differences in facial recognition between participants who responded to the automatic condition and participants who responded to the controlled condition of the Stroop task did not differ significantly. The results suggest that the processing shift from configural to featural processing, which is induced by the Navon letters, would better explain the verbal overshadowing effect than the processing modes underlying the Stroop task.

Generalization decrement and not overshadowing by associative competition among pairs of landmarks in a navigation task.

When they are trained in a Morris water maze to find a hidden platform, whose location is defined by a number of equally spaced visual landmarks round the circumference of the pool, rats are equally able to find the platform when tested with any two of the landmarks (Prados, & Trobalon, 1998; Rodrigo, Chamizo, McLaren, & Mackintosh, 1997). This suggests that none of the landmarks was completely overshadowed by any of the others. In Experiment 1 one pair of groups was trained with four equally salient visual landmarks spaced at equal intervals around the edge of the pool, while a second pair was trained with two landmarks only, either relatively close to or far from the hidden platform. After extensive training, both male and female rats showed a reciprocal overshadowing effect: on a test with two landmarks only (either close to or far from the platform), rats trained with four landmarks spent less time in the platform quadrant than those trained with only two. Experiment 2 showed that animals trained with two landmarks and then tested with four also performed worse on test than those trained and tested with two landmarks only. This suggests that generalization decrement, rather than associative competition, provides a sufficient explanation for the overshadowing observed in Experiment 1. Experiment 3 provided a within-experiment replication of the results of Experiments 1 and 2. Finally, Experiment 4 showed that rats trained with a configuration of two landmarks learn their identity.

Overshadowing between landmarks on the touchscreen and in arena with pigeons.

The role of generalization decrement in spatial overshadowing was evaluated using a landmark-based spatial search task in both a touchscreen preparation (Experiment 1a) and in an Automated Remote Environmental Navigation Apparatus (ARENA, Experiment 1b). A landmark appeared as a colored circle among a row of eight (touchscreen) or six (ARENA) potential locations. On overshadowing trials, Landmark X was located two positions away from a hidden goal, while another landmark, A, was in the position between X and the goal. On control trials, Landmark Y was positioned two locations away from the goal but without a closer landmark. All subjects were then tested with separate trials of A, X, Y, and BY. Testing revealed poor spatial control by X relative to A and Y, thereby replicating the spatial overshadowing effect. Spatial control by Y was similar when tested in compound with novel landmark (BY) and on trials of Y alone. Thus, overshadowing in a small-scale environment does not appear to be due to a process of generalization decrement between training and testing.

Remembering, Recognizing and Describing Singers' Sound Identities

Perceiving music performers through sound quality is important for musicians, teachers and every music listener. A performer's musical identity is influenced by the unique sound they create, yet little is known about listeners' mental representation of an individual's sound quality. A verbal overshadowing (VO) effect has been extensively reported in visual recognition, where the act of verbal description distorts subsequent recall, and the same may apply in the auditory domain and specifically, in music performance reception. In this study we explore if musicians also exhibit a VO effect, by investigating how listeners form auditory impressions of a singer and testing the impact of verbal description on listeners' recognition accuracy and confidence. Listeners (n = 50) heard a single target voice and were assigned to either a verbal description group or a control group. The verbal group wrote a detailed description of the target voice and the control group did not. All listeners heard a voice line-up (n = 6) and were asked to identify the original target voice and rate their confidence in the decision. There was a reliable VO effect where providing a verbal description reduced listeners' identification accuracy of the target voice, but did not reduce listeners' confidence rating of their decision. Verbalization of singing voices was an inadequate representation of listeners' auditory experience and limited listeners' ability to recall and identify singers' sound quality. These results have profound implications for the way in which we consider musical performance and how music listeners recognize, process and describe a performer's sound.

Person descriptions and person identifications: Verbal overshadowing or recognition criterion shift?

In order to test rival theoretical accounts of the verbal overshadowing effect, participants (N=144) either gave no description or provided written descriptions after viewing a crime on video. Half of the describers reread their target descriptions prior to attempting to identify the thief either in a target-absent or target-present lineup 1 week later. Rereaders showed a criterion shift, that is, they less frequently chose somebody from the lineup than the other two groups. Within rereaders, description accuracy and choosing were positively correlated whereas number of incorrect details reported were negatively correlated with choosing. For describers that did not reread their description, there was a significant positive correlation between description accuracy and identification accuracy, and a negative correlation between number of incorrect descriptors and identification accuracy. The results lend support to the decision criterion shift approach (Clare & Lewandowsky, 2004) and shed light on the decision processes underlying target description and identification.

The role of verbal processing at different stages of recognition memory for faces

Four experiments examined the role of verbal processing at different stages of face recognition memory. In Experiment 1 participants learned faces with or without articulatory suppression, then engaged in an old/new recognition task. Using the same procedure, Experiment 2 examined performance under single and dual encoding conditions, using articulatory suppression and face verbalisation. In Experiment 3 performance deriving from these conditions was compared with a tapping control. The results were consistent; articulatory suppression impaired performance in comparison to the other conditions, which themselves did not differ. Experiment 4 examined the effects of postencoding verbalisation on performance, and showed some evidence for a standard verbal overshadowing effect. These results suggest that the role of verbal processing in face memory is complex, depending on the time when such processes occur. The results are discussed with reference to theories of verbal overshadowing.

Testing alternatives to Navon letters to induce a transfer-inappropriate processing shift in face recognition

Processing the local features of a Navon letter (a large global letter made up of small letters) causes a reduction in face identification accuracy (Macrae & Lewis, 2002). This is similar to the verbal overshadowing effect (where describing a face causes it to be less well recognised, see e.g., Schooler & Engstler-Schooler, 1990). Three experiments are presented that explore this Navon effect. Experiment 1 replicates the Navon effect using a new set of stimuli. Experiment 2 extends the effect using Navon shapes in a manner that removes verbal responses. Extending the logic of the proposed transfer-inappropriate processing shift explanation, Experiment 3 attempted to show the same effect using spatial-frequency filtered faces as an induction akin to Navon stimuli. The equivalent effect was not observed. We discuss whether the results indicate that the Navon effect is due to a different mechanism from the verbal overshadowing effect.

From chair to "chair": A representational shift account of object labeling effects on memory.

What are the consequences of calling things by their names? Six experiments investigated how classifying familiar objects with basic-level names (chairs, tables, and lamps) affected recognition memory. Memory was found to be worse for items that were overtly classified with the category name--as reflected by lower hit rates--compared with items that were not overtly classified. This effect of labeling on subsequent recall is explained in terms of a representational shift account, with labeling causing a distortion in dimensions most reliably associated with the category label. Consistent with this account, effects of labeling were strongly mediated by typicality and ambiguity of the labeled items, with typical and unambiguous items most affected by labeling. Follow-up experiments showed that this effect cannot be explained solely by differences in initial encoding, further suggesting that labeling a familiar image distorts its encoded representation. This account suggests a possible mechanism for the verbal overshadowing effect (J. W. Schooler & T. Y. Engstler-Schooler, 1990).

Articulatory suppression attenuates the verbal overshadowing effect: a role for verbal encoding in face identification

Verbal overshadowing is the phenomenon that verbally describing a face between presentation and test can impair identification of the face (Schooler & Engstler-Schooler, 1990). This study examined the effects of articulatory suppression and distinctiveness upon the magnitude of the verbal overshadowing effect. Participants engaged in articulatory suppression or a control task whilst viewing a target face. They then either described the face or completed a distractor task before selecting the target face from a line-up. This was repeated for 12 trials. Articulatory suppression impaired identification performance overall, and reduced the negative effects of description to non-significance, whereas the control group demonstrated the standard verbal overshadowing effect. Typical faces showed verbal overshadowing, whereas distinctive faces did not. These results are consistent with the view that verbal overshadowing arises because the description of the target face creates a verbal code that interferes with a verbal code created spontaneously during encoding. Copyright © 2006 John Wiley & Sons, Ltd.

Verbal overshadowing: a sound theory in voice recognition?

SUMMARY Verbal overshadowing is the impairment of a person’s recognition ability as a result of generating a verbal description. Two experiments involving 169 participants examined the effects of verbal overshadowing, race of voice (own/other) and cognitive style (holistic/analytic) on voice recognition. In Experiment 1, participants heard a recorded voice (own- or other-race) saying a short phrase. After completing a cognitive style analysis and 15-minute filler task, the verbalisation group gave a written description of the voice while the control group did a filler task. Participants then attempted to identify the voice from a 6-voice lineup tape. Experiment 2 manipulated the similarity of the own-race voices by using telephone recordings of the voices, and the encoding-test similarities of the stimuli by using different phrases at encoding and test. Results showed a strong own-race bias with superior own-race voice recognition and no verbal overshadowing in Experiment 1, and a strong verbal overshadowing effect in Experiment 2. Cognitive style was predictive of voice identification in both experiments. Results are discussed with reference to the own-race bias, cognitive style and encoding-test similarity of the stimulus in verbal overshadowing. Copyright # 2005 John Wiley & Sons, Ltd. While much research into human memory has suggested that verbal rehearsal and elaboration of information improves memory performance, a series of experiments by Schooler and Engstler-Schooler in 1990 raised doubt that this is always the case. In their experiments, Schooler and Engstler-Schooler asked participants to watch a 30-second videotape of a staged bank robbery. After a 20-minute delay, during which participants did an unrelated filler task, they were asked either to describe each feature of the robber’s face in detail, or to continue with the filler task. Finally, participants were asked to identify the robber from a line-up of eight verbally similar faces. The results showed that participants who had described the target face were significantly less likely to identify the face. As Schooler and Engstler-Schooler (1990) observed, much of the previous research into memory performance used verbal stimuli, and such stimuli were well-suited to verbal rehearsal and elaboration. In contrast, the modalities of stimulus and task in their own experiments were disparate (visual and verbal), with faces not lending themselves easily to verbal description. They hypothesised that verbal rehearsal or elaboration would be

Perceptual and conceptual training mediate the verbal overshadowing effect in an unfamiliar domain.

Describing memory for a nonverbal perceptual stimulus can impair recognition. This verbal overshadowing effect may occur when perceptual expertise exceeds verbal expertise, but previous evidence for this hypothesis has been strictly correlational. We conducted two experiments, exploring the relation between expertise and verbal overshadowing by manipulating perceptual and conceptual knowledge. Participants received perceptual training (categorizing mushrooms), conceptual training (lecture), or no training, then viewed a mushroom and described it or not. A recognition test followed. In Experiment 1, perceptual training increased susceptibility to verbalization relative to the no training condition. However, conceptual training did not insulate individuals from the verbal overshadowing effect. Experiment 2 was modified to enhance both forms of training. It replicated the finding that perceptual training increases vulnerability to verbal overshadowing, and indicated that, when sufficiently emphasized, verbalization may be useful following conceptual training. The results demonstrate the role that different forms of learning and expertise may play in mediating language influences on recognition memory.

The influence of test‐set similarity in verbal overshadowing

AbstractThe verbal overshadowing effect is the phenomenon in which describing a previously seen face impairs its recognition (Schooler and Engstler‐Schooler, 1990). The primary purpose of this research was to investigate how the similarity between a target and distractors influences verbal overshadowing. In order to manipulate test‐set similarity, we blended the faces of different people by using morphing techniques. As a result, verbal overshadowing was found when test‐set similarity was relatively high, while the effect was not evident when there was a lesser degree of similarity. The results suggest that replicating the emergence of the verbal overshadowing effect depends on test‐set similarity. The implications of these findings for research and practice are discussed. Copyright © 2002 John Wiley & Sons, Ltd.

Verbalization produces a transfer inappropriate processing shift

AbstractWhen considered in the context of prior research, the articles in this special issue on verbal overshadowing largely support the contention that verbalization can induce a processing shift that interferes with the application of non‐verbal operations. Multiple sources of evidence for a processing shift are reviewed, including: (1) verbalization quality often does not correspond to recognition performance; (2) describing one stimulus can interfere with memory for a different stimulus; (3) engaging in a featural processing tasks impairs recognition in a manner comparable to verbalization; and (4) engaging in non‐verbal tasks can reverse the negative effects of verbalization. In the light of this evidence, it is suggested that verbalization produces a ‘transfer inappropriate processing shift’ whereby the cognitive operations engaged in during verbalization dampen the activation of brain regions associated with critical non‐verbal operations. This account of verbal overshadowing is then used to explain both the generality and fragility of the verbal overshadowing effect. Copyright © 2002 John Wiley & Sons, Ltd.

Towards a procedure for eliciting verbal expression of non‐verbal experience without reactivity: interpreting the verbal overshadowing effect within the theoretical framework for protocol analysis

AbstractThe reactive effects of verbal overshadowing are discussed within Ericsson and Simon's (1980, 1984/1993) theoretical framework, which guided the design of procedures that elicit valid and non‐reactive verbal reports. These procedures encourage participants to give free verbal expression to their thoughts. In contrast, the procedures in the verbal overshadowing paradigm require participants to produce prescribed types of verbalizations. Participants are explicitly told how to verbally describe the face, namely ‘to describe each facial feature in as much detail as possible’ and to continue doing so for the full 5 minutes. The reactive effects of ‘verbal overshadowing’ can be linked to the requirement of producing prescribed types of verbalizations and are thus not caused merely by spontaneous verbal expression of one's thoughts. Copyright © 2002 John Wiley & Sons, Ltd.

Verbal overshadowing in voice recognition

AbstractAn experiment examined the influence of three factors on the accuracy and confidence in voice identifications from a voice‐lineup. In a factorial design, participants either encoded the original voice deliberately or were exposed incidentally, either heard a normal voice, or a voice recorded through a telephone, and either described a target voice prior to the lineup or they did not. The method of encoding had no impact on performance, whilst hearing a telephone voice reduced confidence without impairing accuracy. Providing a verbal description impaired subsequent identification accuracy (a verbal overshadowing effect), without reducing confidence. Thus, these data demonstrate that verbal overshadowing can occur in voice recognition, and also provide another dissociation between confidence and performance. Copyright © 2002 John Wiley & Sons, Ltd.

Verbal overshadowing: A special issue exploring theoretical and applied issues

AbstractOver a decade of research has investigated the verbal overshadowing effect. This phenomenon, first demonstrated by Schooler and Engstler‐Schooler (1990), indicates that verbally describing a non‐verbal stimulus (such as a face) can impair subsequent attempts at identification of the stimulus. Taken together, the current special issue on verbal overshadowing explores three critical aspects of the effect: (a) debates regarding the theoretical mechanisms governing the phenomenon, (b) boundary conditions that might define when the effect is observed, and (c) new domains and paradigms that explore the generality of the phenomenon. Copyright © 2002 John Wiley & Sons, Ltd.

The effects of exemplar and prototype descriptors on verbal overshadowing

AbstractPrevious research has found that providing a verbal description for a face impedes later recognition of that face. The current experiment evaluates how the type of information participants are asked to provide about the face affects later recognition. Participants provided attribute, exemplar or prototype information about a person they saw commit a videotaped crime. The verbal overshadowing effect was replicated for participants in the attribute condition. Exemplar participants reproduced this effect, while prototype participants performed nearly as well as controls. Theoretical and practical implications of the type of information witnesses are asked to provide are discussed. Copyright © 2002 John Wiley & Sons, Ltd.

A meta‐analysis of the verbal overshadowing effect in face identification

AbstractRecent studies have demonstrated that requesting individuals to produce a verbal description of a previously seen face can hinder subsequent attempts at identification. This phenomenon, termed ‘verbal overshadowing’, has been studied rather extensively in the face‐identification paradigm; however, studies have not always replicated the general effect. Based upon both practical and theoretical interests in the phenomenon, a meta‐analysis of 29 effect size comparisons (N = 2018) was conducted. Across the sample of studies there was a small, yet significant, negative effect (Fisher's Zr = −0.12), indicating some degree of verbal impairment or overshadowing. A fixed‐effects analysis of several moderating variables demonstrated a significant effect of post‐description delay and type of description instruction. The pattern of means indicated that overshadowing effects were more likely to occur when the identification task immediately followed the description task, and when participants were given an elaborative, as opposed to a standard (free recall), instruction during the description task. Inconsistencies in the literature are discussed, as well as various theoretical and applied issues regarding the verbal overshadowing effect. Copyright © 2001 John Wiley & Sons, Ltd.

Influence of a beacon on spatial learning based on the shape of the test environment.

In 5 experiments rats were required to escape from a triangular shaped pool by swimming to a submerged platform. The principal group of interest in each experiment received training with a beacon attached to the platform. The purpose of the experiments was to assess if the beacon overshadowed (Experiments 1–4) or blocked (Experiment 5) learning about the position of the platform with reference to the shape of the pool. The platform was located in the center of the pool for the first 2 experiments and in a corner for the remaining experiments. Although there was an overshadowing effect in Experiment 1, the remaining experiments failed to reveal any disruptive influence of the beacon on learning based on the shape of the pool. Moreover, in Experiments 3–5 there was an indication that the beacon facilitated such learning. The results suggest that spatial learning based on the shape of a test environment may not take place in the same way as that based on more discrete landmarks.