Changing scenes: memory for naturalistic events following change blindness

Research on scene perception indicates that viewers often fail to detect large changes to scene regions when these changes occur during a visual disruption such as a saccade or a movie cut. In two experiments, we examined whether this relative inability to detect changes would produce systematic biases in event memory. In Experiment 1, participants decided whether two successively presented images were the same or different, followed by a memory task, in which they recalled the content of the viewed scene. In Experiment 2, participants viewed a short video, in which an actor carried out a series of daily activities, and central scenes' attributes were changed during a movie cut. A high degree of change blindness was observed in both experiments, and these effects were related to scene complexity (Experiment 1) and level of retrieval support (Experiment 2). Most important, participants reported the changed, rather than the initial, event attributes following a failure in change detection. These findings suggest that attentional limitations during encoding contribute to biases in episodic memory.     

Metacognition and change detection: do lab and life really converge?

Studies of change blindness indicate that more intentional monitoring of changes is necessary to successfully detect changes as scene complexity increases. However, there have been conflicting reports as to whether people are aware of this relation between intention and successful change detection as scene complexity increases. Here we continue our dialogue with [Beck, M. R., Levin, D. T., & Angelone, B. (2007a). Change blindness blindness: Beliefs about the roles of intention and scene complexity in change detection. Consciousness and Cognition, 16, 31-51; Beck, M. R., Levin, D. T., & Angelone, B. (2007b). Metacognitive errors in change detection: Lab and life converge. Consciousness and Cognition, 16, 58-62] by reporting two experiments that show participants do in fact intuit that more intentional monitoring is needed to detect changes as scene complexity increases. We also discuss how this dialogue illustrates the need for psychological studies to be grounded in measurements taken from real world situations rather than laboratory experiments or questionnaires.     

Metacognitive errors in change detection: missing the gap between lab and life

Studies of change detection suggest that people tend to overestimate their ability to detect visual changes. In a recent laboratory study of change detection and human intention, Beck et al., found that individuals have an inadequate understanding that intention can improve change detection performance and that its importance increases with scene complexity. We note that these findings may be specific to unfamiliar situations such as those generated routinely in studies of change detection. In two questionnaire studies, we demonstrate that when participants consider real world scenarios such as driving, people are well aware that the intention to detect changes improves detection performance, especially in complex scenes. We suggest several reasons why change detection findings like Beck et al.'s do not generalize to real world situations. More broadly, we suggest a possible way to bridge the gap between lab and life.     

Sustained change blindness to incremental scene rotation: a dissociation between explicit change detection and visual memory

In a change detection paradigm, the global orientation of a natural scene was incrementally changed in 1 degree intervals. In Experiments 1 and 2, participants demonstrated sustained change blindness to incremental rotation, often coming to consider a significantly different scene viewpoint as an unchanged continuation of the original view. Experiment 3 showed that participants who failed to detect the incremental rotation nevertheless reliably detected a single-step rotation back to the initial view. Together, these results demonstrate an important dissociation between explicit change detection and visual memory. Following a change, visual memory is updated to reflect the changed state of the environment, even if the change was not detected.     

Change blindness and visual memory: Visual representations get rich and act poor

Change blindness is often taken as evidence that visual representations are impoverished, while successful recognition of specific objects is taken as evidence that they are richly detailed. In the current experiments, participants performed cover tasks that required each object in a display to be attended. Change detection trials were unexpectedly introduced and surprise recognition tests were given for nonchanging displays. For both change detection and recognition, participants had to distinguish objects from the same basic‐level category, making it likely that specific visual information had to be used for successful performance. Although recognition was above chance, incidental change detection usually remained at floor. These results help reconcile demonstrations of poor change detection with demonstrations of good memory because they suggest that the capability to store visual information in memory is not reflected by the visual system's tendency to utilize these representations for purposes of detecting unexpected changes.     

Evidence for preserved representations in change blindness

People often fail to detect large changes to scenes, provided that the changes occur during a visual disruption. This phenomenon, known as "change blindness," occurs both in the laboratory and in real-world situations in which changes occur unexpectedly. The pervasiveness of the inability to detect changes is consistent with the theoretical notion that we internally represent relatively little information from our visual world from one glance at a scene to the next. However, evidence for change blindness does not necessarily imply the absence of such a representation---people could also miss changes if they fail to compare an existing representation of the pre-change scene to the post-change scene. In three experiments, we show that people often do have a representation of some aspects of the pre-change scene even when they fail to report the change. And, in fact, they appear to "discover" this memory and can explicitly report details of a changed object in response to probing questions. The results of these real-world change detection studies are discussed in the context of broader claims about change blindness.     

Visual long-term memory and change blindness: Different effects of pre- and post-change information on one-shot change detection using meaningless geometric objects

To clarify the relationship between visual long-term memory (VLTM) and online visual processing, we investigated whether and how VLTM involuntarily affects the performance of a one-shot change detection task using images consisting of six meaningless geometric objects. In the study phase, participants observed pre-change (Experiment 1), post-change (Experiment 2), or both pre- and post-change (Experiment 3) images appearing in the subsequent change detection phase. In the change detection phase, one object always changed between pre- and post-change images and participants reported which object was changed. Results showed that VLTM of pre-change images enhanced the performance of change detection, while that of post-change images decreased accuracy. Prior exposure to both pre- and post-change images did not influence performance. These results indicate that pre-change information plays an important role in change detection, and that information in VLTM related to the current task does not always have a positive effect on performance.     

The effects of humor on memory for non-sensical pictures

Two experiments investigated the effects of humor on memory for non-sensical pictures. Each picture was given three labels that differed in the degree of humor: high, low, and no humor labels. In Experiment 1, the humor of the picture labels was manipulated between participants. Participants were shown 30 pictures for 10 s each and were asked to rate the degree of humor of each picture. After the rating task, participants were asked to draw the pictures in an unexpected memory test. Performance in the memory test was best in the high humor label group, followed by the low and the no humor label groups. In Experiment 2, intention to learn (incidental versus intentional encoding tasks) as well as humor label was manipulated between the participants. In the incidental learning condition, the high humor group performed better than the low humor group, but in the intentional learning condition, there was no humor effect. The effects of humor on picture memory were discussed in terms of appraisal processing within a distinctiveness framework.     

Incidental visual memory for objects in scenes

Three experiments were conducted to investigate the existence of incidentally acquired, long-term, detailed visual memory for objects embedded in previously viewed scenes. Participants performed intentional memorization and incidental visual search learning tasks while viewing photographs of real-world scenes. A visual memory test for previously viewed objects from these scenes then followed. Participants were not aware that they would be tested on the scenes following incidental learning in the visual search task. In two types of memory tests for visually specific object information (token discrimination and mirror-image discrimination), performance following both the memorization and visual search conditions was reliably above chance. These results indicate that recent demonstrations of good visual memory during scene viewing are not due to intentional scene memorization. Instead, long-term visual representations are incidentally generated as a natural product of scene perception.     

Attentional enhancement opposite a peripheral flash revealed using change blindness

We describe a new method for mapping spatial attentionthat reveals a pooling of attention in the hemifield opposite a peripheralflash. Our method exploits the fact that a brief full-field blank caninterfere with the detection of changes in a scene that occur during theblank. Attending to the location of a change, however, can overcome thischange blindness, so that changes are detected. The likelihood of detecting anew element in a scene therefore provides a measure of the occurrence ofattention at that element's location. Using this measure, we mappedhow attention changes in response to a task-irrelevant peripheral cue. Underconditions of visual fixation, change detection was above chance across theentire visual area tested. In addition, a "hot spot" ofattention (corresponding to near-perfect change detection) elongated alongthe cue-fixation axis, such that performance improved not only at the cuedlocation but also in the opposite hemifield.     

Change blindness and eyewitness testimony

The authors explored the relevance of research on change blindness to eyewitness identification and testimony under intentional and incidental memory conditions. Participants (N = 80, 40 men and 40 women) viewed a video enactment of a burglary in which the identity of the burglar changed at the halfway point of the film. Half of participants were briefed to remember the content, and the other half were not. All were tested for the recall of the content, awareness of the change, and ability to identify either or both of the burglars. Some 61% of participants did not notice the identity change. Rates of detection were significantly higher in participants in the intentional condition, who also recalled significantly more detail from the film. Awareness of change was also significantly related to content recall scores and accuracy of identification of both burglars. The results illustrate the interrelation between the eyewitness and change blindness literatures.     

The relationship between online visual representation of a scene and long-term scene memory

In 3 experiments the author investigated the relationship between the online visual representation of natural scenes and long-term visual memory. In a change detection task, a target object either changed or remained the same from an initial image of a natural scene to a test image. Two types of changes were possible: rotation in depth, or replacement by another object from the same basic-level category. Change detection during online scene viewing was compared with change detection after delay of 1 trial (Experiments 2A and 2B) until the end of the study session (Experiment 1) or 24 hr (Experiment 3). There was little or no decline in change detection performance from online viewing to a delay of 1 trial or delay until the end of the session, and change detection remained well above chance after 24 hr. These results demonstrate that long-term memory for visual detail in a scene is robust.     

The effects of scene inversion on change blindness

In two experiments, participants searched for a difference between two views of a scene. In Experiment 1, the authors extended the change-blindness findings from previous work by R. A. Rensink, J. K. O'Regan, and J. J. Clark (1997), which used an experimenter-induced global transient, to a less artificial situation in which participants searched for a difference in a pair of photographic images presented simultaneously. To examine the idea that meaning-driven endogenous orienting was responsible for the previously observed advantage for changes in center-of-interest items, the authors inverted half of the image pairs. The advantage for center-of-interest items was replicated with upright displays, but it was completely eliminated by inversion, strongly supporting the role of meaning-driven endogenous orienting in this task. With flickering displays (Experiment 2), the center-of-interest effect was completely unaffected by inversion. The authors suggest that when change blindness is induced via flicker, scene modifications are typically found by stimulus-driven rather than by meaning-driven processes.     

Memory for temporal context: effects of ageing, encoding instructions, and retrieval strategies

Young and older adults were compared on a list discrimination task. In Experiment 1, performance declined with ageing after incidental and intentional encoding of the temporal context. Moreover, there was no benefit for intentional encoding in either group. In Experiment 2, each list was associated with a different encoding context. There were age differences in performance when participants tried to retrieve the encoding context of the items as a cue for their list of occurrence, but not when participants evaluated temporal distance from the strength of the memory trace. This suggests that the age-related decrease in list discrimination could be at least partly due to a difficulty in inferring strategically the temporal context of the items from information encoded in the same time.     

Aging, imagery, and the bizarreness effect

ABSTRACT This study examined the bizarre imagery effect in young and older adults, under incidental and intentional conditions. Intentionality was manipulated across experiments, with participants receiving an incidental free recall test in Experiment 1 and an intentional test in Experiment 2. This study also examined the relation between working memory resources and the bizarreness effect. In Experiment 1 young and older adults were presented with common and bizarre sentences; they later received an incidental recall test. There were no age differences in sensitivity to the bizarreness effect in Experiment 1 when ANOVAs were used to analyze the data. However, when the bizarreness effect was examined in terms of effect size, there was evidence that younger adults produced larger bizarreness effect sizes than younger adults. Experiment 2 further explored age differences in sensitivity to the bizarreness effect by presenting young and older adults with bizarre and common sentences under intentional learning conditions. Experiment 2 failed to yield age differences as a function of item type (bizarre vs. common). In addition, Experiment 2 failed to yield significant evidence that the bizarreness effect is modulated by working memory resources. The results of this study are most consistent with the distinctiveness account of the bizarreness effect.     

Reflexive attention attenuates change blindness (but only briefly)

Humans are remarkably insensitive to large changes in a visual display if the change occurs simultaneously with a secondary perceptual event. A widely held view is that this change blindness occurs because the secondary perceptual event prevents the change from capturing attention. However, whereas some studies have shown that top-down attentional priming can attenuate change blindness, the evidence regarding the effect of bottom-up attentional capture on change blindness is less clear-cut. Here, we compare the effects of attentional capture on change detection with participants' performance on a well-established attentional paradigm (a Posner-style cuing task). Experiment 1 established the time course of attentional capture in our paradigm. Experiment 2 demonstrated that this attentional capture was associated with facilitated change detection at short (150-msec), but not long (480-msec), latencies. These data show that reflexive attentional shifts facilitate change detection and are consistent with the view that shifts of attention are a necessary precondition for visual awareness.     

Aging,imagery, and the bizarreness effect

ABSTRACT

This study examined the bizarre imagery effect in young and older adults, under incidental and intentional conditions. Intentionality was manipulated across experiments, with participants receiving an incidental free recall test in Experiment 1 and an intentional test in Experiment 2. This study also examined the relation between working memory resources and the bizarreness effect. In Experiment 1 young and older adults were presented with common and bizarre sentences; they later received an incidental recall test. There were no age differences in sensitivity to the bizarreness effect in Experiment 1 when ANOVAs were used to analyze the data. However, when the bizarreness effect was examined in terms of effect size, there was evidence that younger adults produced larger bizarreness effect sizes than younger adults. Experiment 2 further explored age differences in sensitivity to the bizarreness effect by presenting young and older adults with bizarre and common sentences under intentional learning conditions. Experiment 2 failed to yield age differences as a function of item type (bizarre vs. common). In addition, Experiment 2 failed to yield significant evidence that the bizarreness effect is modulated by working memory resources. The results of this study are most consistent with the distinctiveness account of the bizarreness effect.     

Does scene context always facilitate retrieval of visual object representations?

An object-to-scene binding hypothesis maintains that visual object representations are stored as part of a larger scene representation or scene context, and that scene context facilitates retrieval of object representations (see, e.g., Hollingworth, Journal of Experimental Psychology: Learning, Memory and Cognition, 32, 58-69, 2006). Support for this hypothesis comes from data using an intentional memory task. In the present study, we examined whether scene context always facilitates retrieval of visual object representations. In two experiments, we investigated whether the scene context facilitates retrieval of object representations, using a new paradigm in which a memory task is appended to a repeated-flicker change detection task. Results indicated that in normal scene viewing, in which many simultaneous objects appear, scene context facilitation of the retrieval of object representations-henceforth termed object-to-scene binding-occurred only when the observer was required to retain much information for a task (i.e., an intentional memory task).     

Mapping visual attention with change blindness: new directions for a new method

Change blindness provides a new technique for mapping visual attention with unprecedented spatial and temporal resolution. Change blindness can occur when a brief full-field blank interferes with the detection of changes in a scene that occur during the blank. This interference can be overcome by attending to the location of a change. Because changes are detected at attended locations, but not at unattended locations, detection accuracy provides an indirect measure of the distribution of visual attention. The likelihood of detecting a new element in a scene provides a measure of the occurrence of attention at that element’s location. Potential new directions, advantages, and problems with this method are considered.     

How Are Different Properties of a Scene Encoded in Visual Memory?

Recent studies in scene perception suggest that much of what observers believe they see is not retained in visual memory. Depending on the roles they play in organizing the perception of a scene, different visual properties may require different amounts of attention to be incorporated into a mental representation of the scene. The goal of this study was to compare how three visual properties of scenes, colour, object position, and object presence, are encoded in visual memory. We used a variation on the change detection “flicker” task and measured the time to detect scene changes when: (1) a cue was provided regarding the type of change; and, (2) no cue was provided. We hypothesized that cueing would enhance the processing of visual properties that require more attention to be encoded into scene representations, whereas cueing would not have an effect for properties that are readily or automatically encoded in visual memory. In Experiment 1, we found that there was a cueing advantage for colour changes, but not for position or presence changes. In Experiment 2, we found the same cueing effect regardless of whether the colour change altered the configuration of the scene or not. These results are consistent with the idea that properties that typically help determine the configuration of the scene, for example, position and presence, are better encoded in scene representations than are surface properties such as colour.