Shuffling your way out of change blindness

Change detection is typically discussed in the literature as a 2-state phenomenon. Small differences between otherwise identical images are easy to detect when the images are superimposed in space and alternated in time (“shuffled”). However, change blindness results from any disruption that prevents the critical change from generating the sole salient transient. Here we show that different presentation strategies produce different degrees of change blindness for the same change. Specifically, shuffling the images supports faster change detection than viewing the same 2 images side by side, even when the images contain a number of distracting differences. In Experiment 1, pairs of photographs having a 50 % chance of containing a difference were viewed either in alternation, in a “Shuffle” condition, or simultaneously, in a “Side-by-Side” condition. Change detection was about 6 seconds faster when the images were viewed in the “Shuffle” mode. In Experiment 2, we presented two images that were slightly laterally shifted relative to each other (0–48 pixels). The RT benefit for the Shuffle viewing mode was very strong when the relative shift was small, to insignificant when there was a large difference between the two images. However, at large shifts, Shuffle maintained an accuracy advantage. It seems that changes are easier to detect when comparing images in a Shuffle condition rather than Side-by-Side. This has important implications for real world tasks like radiology where detection of change is critical.     

Lost in the supermarket: Quantifying the cost of partitioning memory sets in hybrid search

The items on a memorized grocery list are not relevant in every aisle; for example, it is useless to search for the cabbage in the cereal aisle. It might be beneficial if one could mentally partition the list so only the relevant subset was active, so that vegetables would be activated in the produce section. In four experiments, we explored observers’ abilities to partition memory searches. For example, if observers held 16 items in memory, but only eight of the items were relevant, would response times resemble a search through eight or 16 items? In Experiments 1a and 1b, observers were not faster for the partition set; however, they suffered relatively small deficits when “lures” (items from the irrelevant subset) were presented, indicating that they were aware of the partition. In Experiment 2 the partitions were based on semantic distinctions, and again, observers were unable to restrict search to the relevant items. In Experiments 3a and 3b, observers attempted to remove items from the list one trial at a time but did not speed up over the course of a block, indicating that they also could not limit their memory searches. Finally, Experiments 4a, 4b, 4c, and 4d showed that observers were able to limit their memory searches when a subset was relevant for a run of trials. Overall, observers appear to be unable or unwilling to partition memory sets from trial to trial, yet they are capable of restricting search to a memory subset that remains relevant for several trials. This pattern is consistent with a cost to switching between currently relevant memory items.     

The perception of humanness from the movements of synthetic agents

As technology develops, social robots and synthetic avatars might begin to play more of a role in our lives. An influential theory of the perception of synthetic agents states that as they begin to look and move in a more human-like way, they elicit profound discomfort in the observer--an effect known as the Uncanny Valley. Previous attempts to examine the existence of the Uncanny Valley have not adequately manipulated movement parameters that contribute to perceptions of the humanness or eeriness. Here we parametrically manipulated three different kinematic features of two walking avatars and found that, contrary to the Uncanny Valley hypothesis, ratings of the humanness, familiarity, and eeriness of these avatars changed monotonically. Our results indicate that, when a full gradient of motion parameter changes is examined, ratings of synthetic agents by human observers do not show an Uncanny Valley.     

Hybrid search in the temporal domain: Evidence for rapid,serial logarithmic search through memory

In hybrid search, observers memorize a number of possible targets and then search for any of these in visual arrays of items. Wolfe (2012) has previously shown that the response times in hybrid search increase with the log of the memory set size. What enables this logarithmic search of memory? One possibility is a series of steps in which subsets of the memory set are compared to all items in the visual set simultaneously. In the present experiments, we presented single visual items sequentially in a rapid serial visual presentation (RSVP) display, eliminating the possibility of simultaneous testing of all items. We used a staircasing procedure to estimate the time necessary to effectively detect the target in the RSVP stream. Processing time increased in a log–linear fashion with the number of potential targets. This finding eliminates the class of models that require simultaneous comparison of some memory items to all (or many) items in the visual display. Experiment 3 showed that, similar to visual search, memory search efficiency in this paradigm is influenced by the similarity between the target set and the distractors. These results indicate that observers perform separate memory searches on each eligible item in the visual display. Moreover, it appears that memory search for one item can proceed while other items are being categorized as “eligible” or “not eligible.”     

Hybrid search in context: How to search for vegetables in the produce section and cereal in the cereal aisle

ABSTRACT

The own race bias (ORB) refers to a finding that faces of members of one's own racial or ethnic group are easier to recognize. Holistic processing theories suggest that the ORB might be moderated by viewing distance. Participants studied photographs of own and other race individuals and then took a recognition memory test. Viewing distance was simulated by varying the degree to which photographs were blurred (Experiment 1) and by varying photograph size (Experiment 2). Findings indicated that own race faces were better recognized, that recognition was impaired by simulated viewing distance, but the size of the ORB was not contingent upon distance.     

A hybrid model using neural networks and ACT-R

How do people make decisions given contradictory information? This paper presents a model of how expert DSOs (defensive system operators) on a B1 bomber examine a complex series of signals, categorize whether those signals are dangerous or not, and then make a decision on the basis of those signals. This decision is made more difficult because an automatic on-board computer sometimes identifies the signal incorrectly. Therefore, the DSO must compare the actual signal to the system ID “guess.” The proposed model is a hybrid model, combining a standard neural network and ACT-R, a production system, which achieves a high degree of success.     

The effect of stress on craving for methadone depends on the timing of last methadone dose

Background

This study examined the extent to which the timing of last methadone dose moderates the influence of a laboratory stressor on craving for methadone in a sample of methadone maintenance patients.

Methods

Methadone maintenance patients (N = 41) completed a computerized stress manipulation with two levels (low and high stress) on two separate days: (1) immediately following the administration of their standard daily methadone dose and (2) immediately prior to receiving their standard daily dose. The impact of stress, timing of methadone dose and their interaction were examined on self-report measures of stress and craving for methadone.

Results

Craving ratings varied according to the timing of last methadone dose. Immediately following methadone dose (i.e., day 1), there was no effect for stress on craving (0.12; p = 0.30). However, prior to receiving methadone dose (i.e., day 2), the high stress effect on craving was significant (1.51; p < 0.001).

Discussion

The present findings indicate that patients currently receiving methadone maintenance treatment may be particularly vulnerable to stress-related relapse immediately prior to daily methadone dosing.     

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.