Remembering more than meets the eye: a study of memory confusions about incomplete visual information

The purpose of this series of four experiments was to examine the possible role of spontaneous imagery in memory confusions about the way in which visual information had been experienced. After viewing pictures of familiar objects, complete or incomplete in visual form, participants were asked to remember the way in which the objects had been presented. Although, as predicted, memory for the objects themselves was quite good, participants falsely remembered seeing complete versions of pictures that were actually presented as incomplete. These false reports were observed across a variety of encoding and testing conditions. The results suggest that the false reports (referred to here as completion errors) are due to internal representations based on filling-in processes in response to the encoding of incomplete visual information. As such, the results also speak to alternative explanations for the completion errors and, more broadly, to theoretical perspectives that draw on filling-in processes when accounting for object identification and object memory.     

Remembering more than meets the eye: A study of memory confusions about incomplete visual information

The purpose of this series of four experiments was to examine the possible role of spontaneous imagery in memory confusions about the way in which visual information had been experienced. After viewing pictures of familiar objects, complete or incomplete in visual form, participants were asked to remember the way in which the objects had been presented. Although, as predicted, memory for the objects themselves was quite good, participants falsely remembered seeing complete versions of pictures that were actually presented as incomplete. These false reports were observed across a variety of encoding and testing conditions. The results suggest that the false reports (referred to here as completion errors) are due to internal representations based on filling-in processes in response to the encoding of incomplete visual information. As such, the results also speak to alternative explanations for the completion errors and, more broadly, to theoretical perspectives that draw on filling-in processes when accounting for object identification and object memory.     

Investigations of closure processes: What source-monitoring judgments suggest about what is “closing”

On many occasions, the perception of an object is based on incomplete information because portions of the object are occluded from view. Nevertheless, people are able to identify an occluded object, suggesting that the identification is mediated by the activation of completion processes which “fill in” the missing information. Although these completion processes are invoked as causal mechanisms for many phenomena, the processes mediating the “completion” have not been specified. The present experiments tested two potential explanations for closure processes. In each experiment, participants were presented with pictures, complete or incomplete in form, and, on a surprise source-monitoring task, they were then asked to remember whether pictures had been presented complete or incomplete in form. Whether viewing pictures of objects, faces, or camouflaged objects, participants showed a pronounced tendency to claim that incomplete pictures were actually presented complete in form. This bias was evident after the participants described functions for objects (Experiments 1, 1A, and 2), after they evaluated properties of faces (Experiment 4), and after they searched for objects hidden in a complex scene (Experiment 5). However, this bias was not evident after they simply named objects portrayed in pictures (Experiment 3). This bias is interpreted as evidence for the activation of implicit imaginal processing. The results of these experiments are informative in their contribution to our understanding of the bases of closure, an intuitively appealing notion frequently invoked to account for object identification, but, as yet, not fully understood.     

A Dynamic Neural Field Model of Visual Working Memory and Change Detection

ABSTRACT— Efficient visually guided behavior depends on the ability to form, retain, and compare visual representations for objects that may be separated in space and time. This ability relies on a short-term form of memory known as visual working memory. Although a considerable body of research has begun to shed light on the neurocognitive systems subserving this form of memory, few theories have addressed these processes in an integrated, neurally plausible framework. We describe a layered neural architecture that implements encoding and maintenance, and links these processes to a plausible comparison process. In addition, the model makes the novel prediction that change detection will be enhanced when metrically similar features are remembered. Results from experiments probing memory for color and for orientation were consistent with this novel prediction. These findings place strong constraints on models addressing the nature of visual working memory and its underlying mechanisms.     

Understanding metaphors: Is the right hemisphere uniquely involved?

Two divided visual field priming experiments examined cerebral asymmetries for understanding metaphors varying in sentence constraint. Experiment 1 investigated ambiguous words (e.g., SWEET and BRIGHT) with literal and metaphoric meanings in ambiguous and unambiguous sentence contexts, while Experiment 2 involved standard metaphors (e.g., The drink you gave me was a meteor) with sententially consistent and inconsistent targets (i.e., POTENT vs COMET). Similar literal and metaphor priming effects were found in both visual fields across most experimental conditions. However, RH processes also maintained activation of sententially inconsistent literal meanings following metaphoric expressions. These results do not strongly support the RH as the preferred substrate for metaphor comprehension (e.g., ), and suggest that processes in both hemispheres can support metaphor comprehension, although not via identical mechanisms. The LH may utilize sentence constraint to select and integrate only contextually relevant literal and metaphoric meanings, whereas the RH may be less sensitive to sentence context and can maintain the activation of some alternative interpretations. This may be potentially useful in situations where an initial understanding must be revised.     

Test modality affects source monitoring and event-related potentials

Two experiments investigated the effect of test modality (visual or auditory) on source memory and event-related potentials (ERPs). Test modality influenced source monitoring such that source memory was better when the source and test modalities were congruent. Test modality had less of an influence when alternative information (i.e., cognitive operations) could be used to inform source judgments in Experiment 2. Test modality also affected ERP activity. Variation in parietal ERPs suggested that this activity reflects activation of sensory information, which can be attenuated when the sensory information is misleading. Changes in frontal ERPs support the hypothesis that frontal systems are used to evaluate source-specifying information present in the memory trace.     

Accessibility effects on implicit social cognition: the role of knowledge activation and retrieval experiences

Performance on measures of implicit social cognition has been shown to vary as a function of the momentary accessibility of relevant information. The present research investigated the mechanisms underlying accessibility effects of self-generated information on implicit measures. Results from 3 experiments demonstrate that measures based on response compatibility processes (e.g., Implicit Association Test, affective priming with an evaluative decision task) are influenced by subjective feelings pertaining to the ease of retrieving relevant information from memory, whereas measures based on stimulus compatibility processes (e.g., semantic priming with a lexical-decision task) are influenced by direct knowledge activation in associative memory. These results indicate that the mediating mechanisms underlying context effects on implicit measures can differ as a function of the task even when these tasks show similar effects on a superficial level. Implications for research on implicit social cognition and the ease-of-retrieval effect are discussed.     

Boundaries of the relation between conscious recollection and source memory for perceptual details

The relation between conscious recollection and source memory for perceptual details was investigated in three experiments that combined the remember-know paradigm with a multidimensional source monitoring test. Experiment 1 replicated that source memory for perceptual details is better in the case of "remember" than "know" judgments. Experiment 2 showed that the relation between "remember" judgments and source memory for perceptual details is diminished by a semantic orienting task during encoding. Experiment 3 demonstrated that "remember" judgments are related to enhanced source memory for specific and unique kinds of perceptual source information, whereas memory for incomplete and global perceptual source information does not differentiate between "remember" and "know" judgments. The results show that the attentional focus during encoding and the specificity of retrieved source information form boundary conditions for the use of source memory for perceptual details as a basis of "remember" judgments.     

Cognitive processes supporting episodic memory formation in childhood: The role of source memory,binding, and executive functioning

Episodic memories contain various forms of contextual detail (e.g., perceptual, emotional, cognitive details) that need to become integrated. Each of these contextual features can be used to attribute a memory episode to its source, or origin of information. Memory for source information is one critical component in the formation of episodic memories. Likewise, the establishment of episodic memories also requires binding, which reflects the process of encoding the relations among stimuli and provides the experience that certain features of a memory episode belong together. The aims of the present review are to explore the roles of (1) cognitive and neural mechanisms involved in source memory and binding and how the development of these cognitive processes relates to episodic memory formation in childhood and (2) other higher-order cognitive processes, namely executive functioning, in early episodic memory development. We conclude by examining the challenges within this field of research, highlighting the role of other cognitive processes (e.g., sense of self, language, use of strategies) that may contribute to episodic memory formation, addressing areas that can be improved with additional research, and exploring directions for future work.     

Thinking graphically: Connecting vision and cognition during graph comprehension

Task analytic theories of graph comprehension account for the perceptual and conceptual processes required to extract specific information from graphs. Comparatively, the processes underlying information integration have received less attention. We propose a new framework for information integration that highlights visual integration and cognitive integration. During visual integration, pattern recognition processes are used to form visual clusters of information; these visual clusters are then used to reason about the graph during cognitive integration. In 3 experiments, the processes required to extract specific information and to integrate information were examined by collecting verbal protocol and eye movement data. Results supported the task analytic theories for specific information extraction and the processes of visual and cognitive integration for integrative questions. Further, the integrative processes scaled up as graph complexity increased, highlighting the importance of these processes for integration in more complex graphs. Finally, based on this framework, design principles to improve both visual and cognitive integration are described.     

Models of verbal working memory capacity: what does it take to make them work?

Theories of working memory (WM) capacity limits will be more useful when we know what aspects of performance are governed by the limits and what aspects are governed by other memory mechanisms. Whereas considerable progress has been made on models of WM capacity limits for visual arrays of separate objects, less progress has been made in understanding verbal materials, especially when words are mentally combined to form multiword units or chunks. Toward a more comprehensive theory of capacity limits, we examined models of forced-choice recognition of words within printed lists, using materials designed to produce multiword chunks in memory (e.g., leather brief case). Several simple models were tested against data from a variety of list lengths and potential chunk sizes, with test conditions that only imperfectly elicited the interword associations. According to the most successful model, participants retained about 3 chunks on average in a capacity-limited region of WM, with some chunks being only subsets of the presented associative information (e.g., leather brief case retained with leather as one chunk and brief case as another). The addition to the model of an activated long-term memory component unlimited in capacity was needed. A fixed-capacity limit appears critical to account for immediate verbal recognition and other forms of WM. We advance a model-based approach that allows capacity to be assessed despite other important processing contributions. Starting with a psychological-process model of WM capacity developed to understand visual arrays, we arrive at a more unified and complete model.     

Automatic processing, code dissimilarity, and the efficiency of successive memory searches.

Two experiments examined the effects of automatic processing and code dissimilarity on the performance of successive memory searches through a single memory set having the same or different kinds of information (i.e., verbal and spatial). The results of both experiments showed that the total time to complete the successive searches was less when automatic processing was involved compared with when both searches required controlled processing. Performance of the successive searches improved substantially with practice. Both experiments also showed an asymmetrical temporal interference between the two searches. Aspects of the to-be-performed second search did not affect first-search reaction times (RTs), but performing the first search did affect the second-search RTs. The interfering effect of the first search was greatest when controlled processes that used the same code were required for both searches, whether the code was verbal or spatial. Several interpretations are offered for the interference generated by the first search. The joint effects of automatic processing and code dissimilarity are also discussed.     

Iconic memory and visible persistence

There are three senses in which a visual stimulus may be said to persist psychologically for some time after its physical offset. First, neural activity in the visual system evoked by the stimulus may continue after stimulus offset (“neural persistence”). Second, the stimulus may continue to be visible for some time after its offset (“visible persistence”). Finally, information about visual properties of the stimulus may continue to be available to an observer for some time after stimulus offset (“informational persistence”). These three forms of visual persistence are widely assumed to reflect a single underlying process: a decaying visual trace that (1) consists of afteractivity in the visual system, (2) is visible, and (3) is the source of visual information in experiments on decaying visual memory. It is argued here that this assumption is incorrect. Studies of visible persistence are reviewed; seven different techniques that have been used for investigating visible persistence are identified, and it is pointed out that numerous studies using a variety of techniques have demonstrated two fundamental properties of visible persistence: theinverse duration effect (the longer a stimulus lasts, the shorter is its persistence after stimulus offset) and theinverse intensity effect (the more intense the stimulus, the briefer its persistence). Only when stimuli are so intense as to produce afterimages do these two effects fail to occur. Work on neural persistences is briefly reviewed; such persistences exist at the photoreceptor level and at various stages in the visual pathways. It is proposed that visible persistence depends upon both of these types of neural persistence; furthermore, there must be an additional neural locus, since a purely stereoscopic (and hence cortical) form of visible persistence exists. It is argued that informational persistence is defined by the use of the partial report methods introduced by Averbach and Coriell (1961) and Sperling (1960), and the term “iconic memory” is used to describe this form of persistence. Several studies of the effects of stimulus duration and stimulus intensity upon the duration of iconic memory have been carried out. Their results demonstrate that the duration of iconic memory is not inversely related to stimulus duration or stimulus intensity. It follows that informational persistence or iconic memory cannot be identified with visible persistence, since they have fundamentally different properties. One implication of this claim that one cannot investigate iconic memory by tasks that require the subject to make phenomenological judgments about the duration of a visual display. In other words, the so-called “direct methods” for studying iconic memory do not provide information about iconic memory. Another implication is that iconic memory is not intimately tied to processes going on in the visual system (as visible persistence is); provided a stimulus is adequately legible, its physical parameters have little influence upon its iconic memory. The paper concludes by pointing out that there exists an alternative to the usual view of iconic memory as a precategorical sensory buffer. According to this alternative, iconic memory is post-categorical, occurring subsequent to stimulus identification. Here, stimulus identification is considered to be a rapid automatic process which does not require buffer storage, but which provides no information about episodic properties of a visual stimulus. Information about these physical stimulus properties must, in some way, be temporarily attached to a representation of the stimulus in semantic memory; and it is this temporarily attached physical information which constitutes iconic memory.     

Differential use of partial information by good and poor readers

Two interpretations of the poor readers' deficit are examined. According to one interpretation, poor readers are primarily deficient in use of phonetic information, and, thus, their deficit is specific to reading or at least to use of language. A second interpretation is that good and poor readers differ in their ability or tendency to use stimulus attributes—that is, partial information for stimulus identity—and, thus, their deficit is not specific to reading. Three experiments provide evidence favoring the second interpretation. Good and poor readers perform differently in tests of memory—whether or not the stimulus items are coded phonetically—when information about stimulus identity is incomplete due to memory loss and the response measure is sensitive to partial-information use in guessing. Likewise, the two groups perform differently in a perceptual task when information for stimulus identity is partial, but they perform at similar levels when information is complete.     

Aging, source memory, and emotion

In 2 experiments we assessed younger and older adults' ability to remember contextual information about an event. Each experiment examined memory for 3 different types of contextual information: (a) perceptual information (e.g., location of an item); (b) conceptual, nonemotional information (e.g., quality of an item); and (c) conceptual, emotional information (e.g., safety of an item). Consistent with a large literature on aging and source memory, younger adults outperformed older adults when the contextual information was perceptual in nature and when it was conceptual, but not emotional. Age differences in source memory were eliminated, however, when participants recalled emotional source information. These findings suggest that emotional information differentially engages older adults, possibly evoking enhanced elaborations and associations. The data are also consistent with a growing literature, suggesting that emotional processing remains stable with age (e.g., Carstensen & Turk-Charles, 1994, 1998; Isaacowitz, Charles, & Carstensen, 2000).     

Priming effects in picture fragment completion: support for the perceptual closure hypothesis

The perceptual closure hypothesis says that priming will be optimum when just enough information is available in the prime to support closure. Across 5 experiments, a moderately complete fragmented image (Level 4) produced more priming than an almost complete (Level 7) or a very incomplete (Level 1) fragmented image. Only Level 4 priming was improved by increases in prime duration and by showing the prime again after Ss attempted to identify it. Explicit memory played little role in primed fragment completion except for Level 1 priming, in which specific fragment memory was responsible for the entire effect. In contrast, true perceptual learning was shown to be responsible for Level 4 and Level 7 priming. These priming effects cannot be accounted for by the transfer-appropriate procedures approach of Roediger and his colleagues because Level 1 priming produced less transfer to Level 1 identification at test than Level 4 priming did.     

Boundary extension: Findings and theories

A view of a scene is often remembered as containing information that might have been present just beyond the actual boundaries of that view, and this is referred to as boundary extension. Characteristics of the view (e.g., scene or nonscene; close-up or wide-angle; whether objects are cropped, static, or in motion, emotionally neutral or emotionally charged), display (e.g., aperture shape and size; target duration; retention interval; whether probes of memory involve magnification/minification or change in physical distance), and observer (e.g., allocation of attention; age; planned fixation, gaze direction, and eye movements; monocular or binocular viewing; prior exposure; neurological correlates) that influence boundary extension are reviewed. Proposed mechanisms of boundary extension (perceptual, memory, or motion schema; extension–normalization; attentional selection; errors in source monitoring) are discussed, and possible relationships of boundary extension to other cognitive processes (e.g., representational momentum; remembered distance and remembered size; amodal completion; transsaccadic memory) are briefly addressed.     

Temporal integration between visual images and visual percepts

Using a temporal integration task, subjects in 5 experiments were expected to combine information from temporally separated visual presentations. Evidence from these experiments indicated that perceptual information can be integrated with previously generated and currently maintained visual images to form a representation that contains information from each source. Properties and limitations of this integration process were also explored, including the time required to generated the image, the speed at which percepts were integrated with images, and the capacity of the representation. Implications for theories of visual processing and memory are discussed.     

Binding actions and scenes in visual long-term memory

How does visual long-term memory store representations of different entities (e.g., objects, actions, and scenes) that are present in the same visual event? Are the different entities stored as an integrated representation in memory, or are they stored separately? To address this question, we asked observers to view a large number of events; in each event, an action was performed within a scene. Afterward, the participants were shown pairs of action–scene sets and indicated which of the two they had seen. When the task required recognizing the individual actions and scenes, performance was high (80 %). Conversely, when the task required remembering which actions had occurred within which scenes, performance was significantly lower (59 %). We observed this dissociation between memory for individual entities and memory for entity bindings across multiple testing conditions and presentation durations. These experiments indicate that visual long-term memory stores information about actions and information about scenes separately from one another, even when an action and scene were observed together in the same visual event. These findings also highlight an important limitation of human memory: Situations that require remembering actions and scenes as integrated events (e.g., eyewitness testimony) may be particularly vulnerable to memory errors.     

Aging and reflective processes of working memory: binding and test load deficits

It was hypothesized that age-related deficits in episodic memory for feature combinations (e.g., B. L. Chalfonte & M. K. Johnson, 1996) signal, in part, decrements in the efficacy of reflective component processes (e.g., M. K. Johnson, 1992) that support the short-term maintenance and manipulation of information during encoding (e.g., F. 1. M. Craik. R. G. Morris. & M. L. Gick, 1990; T. A. Salthouse, 1990). Consistent with this, age-related binding deficits in a working memory task were found in 2 experiments. Evidence for an age-related test load deficit was also found: Older adults had greater difficulty than young adults when tested on 2 features rather than 1, even when binding was not required. Thus, disruption of source memory in older adults may involve deficits in both encoding processes (binding deficits) and monitoring processes (difficulty accessing multiple features, evaluating them, or both).