Embodied perception of reachable space: how do we manage threatening objects?

This study aimed at determining whether the size of reachable space is affected by the level of danger of some everyday manipulable objects. Two possibilities are examined: Dangerous objects affect the size of reachable space because of long-term semantic knowledge of their potential hurtful value or the on-line relation between objects' dangerous attributes and the body. The experimental paradigm combined the danger value (dangerous/not dangerous) and the orientation of objects (e.g. pointing away from/towards the perceiver). Reachability judgments measured the size of peripersonal space, and perception of objects' danger was estimated through questionnaires. Results revealed that, whatever the estimated level of objects' danger, the extent of peripersonal space was reduced when the threatening part of dangerous objects was oriented towards participants, not when oriented away. This suggests that the characteristics of the here and now body-objects interaction are crucial in affecting the boundary of peripersonal space.     

How do we track invisible objects?

We previously demonstrated that observers in multiple object tracking experiments can successfully track targets when all the objects simultaneously vanish for periods lasting several hundred milliseconds (Alvarez, Horowitz, Arsenio, Dimase, &; Wolfe, 2005). How do observers do this? Since observers can track objects that move behind occluders (e.g., Scholl &; Pylyshyn, 1999), they may treat a temporal gap as a case of complete occlusion. If so, performance should improve if occlusion cues (deletion and accretion) are provided and items disappear and reappear one by one (asynchronously), rather than simultaneously. However, we found better performance with simultaneous than with asynchronous disappearance (Experiment 1), whereas occlusion cues were detrimental (Experiment 2). We propose that observers tolerate a gap in tracking by storing the current task state when objects vanish and resuming tracking on the basis of that memory when the objects reappear (a task-switching account).     

Judging relationships between events: how do we do it?

A decade ago, Allan (1993) concluded that associative models provided the best account of data generated in tasks that require human observers to judge the relationship between binary events. In the intervening years, new data have been reported that provide evidence for higher-order processes. Some have argued that these new data pose a serious threat to the viability of the associative account. The purpose of the present paper is to review this evidence and to assess the severity of this threat.     

Timing of multiple overlapping intervals: how many clocks do we have?

Humans perceive and reproduce short intervals of time (e.g. 1-60 s) relatively accurately, and are capable of timing multiple overlapping intervals if these intervals are presented in different modalities [e.g., Rousseau, L., & Rousseau, R. (1996). Stop-reaction time and the internal clock. Perception and Psychophysics, 58(3), 434-448]. Tracking multiple intervals can be explained either by assuming multiple internal clocks or by strategic arithmetic using a single clock. The underlying timescale (linear or nonlinear) qualitatively influences the predictions derived from these accounts, as assuming a nonlinear timescale introduces systematic errors in added or subtracted intervals. Here, we present two experiments that provide support for a single clock combined with a nonlinear underlying timescale. When two equal but partly overlapping time intervals had to be estimated, the second estimate was positively correlated with the stimulus onset asynchrony. This effect was also found in a second experiment with unequal intervals that showed evidence of subtraction of intervals. The findings were supported by computational models implemented in a previously validated account of interval timing [Taatgen, N. A., Van Rijn, H., & Anderson, J. R. (2007). An integrated theory of prospective time interval estimation: The role of cognition, attention and learning. Psychological Review, 114(3), 577-598].     

Can we imagine how objects look from other viewpoints?

Many psychologists who study cognition believe that perception achieves object-centered representations that make it possible to extract representations of how the object would appear from differing viewpoints. Others believe we can achieve representations of how an object would appear by a process of visualization or mental rotation. We report experiments in which the subject tries to imagine how three-dimensional novel wire objects would appear from positions other than the one they are in. Subjects are unable to perform this task unless they make use of strategies that circumvent the process of visualization. It is suggested that the linear increase in time required to succeed in mental rotation tasks as a function of the angular discrepancy between the figures compared is the result of increasing difficulty rather than of the time required for rotation.     

Evaluating evidence of psychological adaptation: how do we know one when we see one?

Evolutionary psychologists argue that human nature contains many discrete psychological adaptations. Each adaptation is theorized to have been functional in humans' ancestral past, and empirical evidence that an attribute is an adaptation can come from showing it possesses complexity, efficiency, universality, and other features of special design. In this article, we present a tutorial review of the evidentiary forms that evolutionary psychologists commonly use to document the existence of human adaptations. We also present a heuristic framework for integrating and evaluating cross-disciplinary evidence of adaptation. Pregnancy sickness, incest avoidance, men's desires for multiple sex partners, and an easily learned fear of snakes are evaluated as possible human adaptations using this framework. We conclude that future research and teaching in evolutionary psychology would benefit from more fully utilizing cross-disciplinary frameworks to evaluate evidence of human adaptation.     

Unification: What is it,how do we Reach and why do we Want it?

This article has three aims. The first is to give a partial explication of the concept of unification. My explication will be partial because I confine myself to unification of particular events, because I do not consider events of a quantitative nature, and discuss only deductive cases. The second aim is to analyze how unification can be reached. My third aim is to show that unification is an intellectual benefit. Instead of being an intellectual benefit unification could be an intellectual harm, i.e., a state of mind we should try to avoid by all means. By calling unification an intellectual benefit, we claim that this form of understanding has an intrinsic value for us. I argue that unification really has this alleged intrinsic value. This revised version was published online in June 2006 with corrections to the Cover Date.     

Do objects in working memory compete with objects in perception?

It is generally assumed that “perceptual object” is the basic unit for processing visual information and that only a small number of objects can be either perceptually selected or encoded in working memory (WM) at one time. This raises the question whether the same resource is used when objects are selected and tracked as when they are held in WM. In two experiments, we measured dual-task interference between a memory task and a Multiple Object Tracking task. The WM tasks involve explicit, implicit, or no spatial processing. Our results suggest there is no resource competition between working memory and perceptual selection except when the WM task requires encoding spatial properties.     

Cognitions associated with attempts to empathize: how do we imagine the perspective of another?

Although the theoretical importance of perspective taking has long been recognized, surprisingly little work has documented the cognitions associated with attempts to imagine another's point of view. To explore this issue and to determine whether perspective taking increases the likelihood of self-related thoughts, two experiments were carried out. In the first, a thought-listing procedure was used to assess observer cognitions; in the second, a less reactive measure was used. Instructions to imagine the self in the target's position and instructions simply to imagine the target's perspective produced increased levels of self-related cognition relative to a traditional control condition; the imagine-self condition also produced more self-thoughts and fewer target thoughts than did the imagine-target condition. The control condition produced thoughts suggesting that the observers were distancing themselves from the target. Observers receiving no instructions at all reported cognitions that closely resembled those of observers who received imagine-target instructions.     

How little do we need for 3-D shape perception?

How little do we need to perceive 3-D shape in monocular natural images? The shape-from-texture and shape-from-shading perspectives would motivate that 3-D perception vanishes once low-level cues are disrupted. Is this the case in human vision? Or can top-down influences salvage the percept? In this study we probe this question by employing a gauge-figure paradigm similar to that used by Koenderink et al (1992, Perception & Psychophysics 52 487-496). Subjects were presented degraded natural images and instructed to make local assessments of slant and tilt at various locations thereby quantifying their internal 3-D percept. Analysis of subjects' responses reveals recognition to be a significant influence thereby allowing subjects to perceive 3-D shape at high levels of degradation. Specifically, we identify the 'medium-blur' condition, images approximately 32 pixels on a side, to be the limit for accurate 3-D shape perception. In addition, we find that degradation affects the perceived slant of point-estimates making images look flatter as degradation increases. A subsequent condition that eliminates texture and shading but preserves contour and recognition reveals how bottom-up and top-down cues can combine for accurate 3-D shape perception.     

Susceptibility to memory distortion: how do we decide it has occurred?

When given suggestive information, some people can be led to believe that they had experiences that they did not actually have. For example, they may come to believe falsely that they got sick eating particular foods as children, and as a result of that belief they may avoid the foods. But how do we know that someone has developed a false belief or memory in this research? The criteria we choose when classifying whether someone has fallen for the suggestion are somewhat arbitrary. We reanalyze our prior data, using different criteria for deciding that a person fell for the suggestion (called a "believer") or did not (called a "non-believer"). Changing criteria obviously affects the percentage of people who are called susceptible and could conceivably affect the conclusions reached about that group. Comparisons between false memories and true memories could differ, too, depending on how memories are defined.     

Slowhand: Does time perception change in peri-hand space?

Psychonomic Bulletin & Review - A variety of attentional and perceptual changes occur in peri-hand space, including increases in visual temporal acuity. These changes in cognition have been...     

Imitation by animals: how do they do it?

Imitation is of psychological interest in part because it has cognitive implications for how organisms view the behavior of others, relative to their own behavior. It implies the ability to take the perspective of another. For this reason, researchers have tried to distinguish imitation from other kinds of social learning and influence. In the two-action procedure, one of two response topographies is demonstrated, and the correlation between the topography demonstrated and the topography later used by the observer is a measure of imitation. Both pigeons and Japanese quail show response matching, despite the fact that from their perspective, their own behavior appears quite different from that demonstrated. Although imitation has been demonstrated in birds and several species of primates, researchers are still not certain what mechanisms underlie this ability.     

What is episodic memory and how do we use it?

What are the neural and computational principles that give rise to episodic memory? Although memory is probably the most studied topic in psychology and cognitive neuroscience, most research has focused on learning at the micro-level. I outline the limitations of this approach and propose a ‘molar’ approach to tackle episodic memory at the scale of life.     

Accuracy of person perception: do people know what kinds of impressions they convey?

Do people know what kinds of impressions they convey to other people during particular social interactions? In a study designed to answer this question, subjects interacted individually with three partners on each of four different tasks. After each interaction, participants reported their impressions of the other person's likability and competence. They also postdicted the impressions they believed they conveyed to the other person along the same dimensions. Accuracy was computed as recommended by Cronbach (1955) and by Kenny's (1981) Social Relations Model. Subjects could tell to a significant degree how the impressions they conveyed to their partners changed over time (time accuracy) and how they changed over time in different ways with different partners (differential accuracy). They could also tell how their competence was differentially perceived by different partners (dyadic accuracy). However, they were not very accurate at discerning which partners perceived them as most competent or most likable across all interactions (person accuracy). Subjects believed that they conveyed similar impressions of themselves to all of their partners, although actually partners evidenced little agreement with each other in their impressions of a given subject. The implications of these findings for symbolic-interactionist theories of the development of the self and impression-management perspectives on social behavior are described.     

Managed care at the bedside: how do we look in the moral mirror?

Managed care per se is a morally neutral concept; however, as practiced today, it raises serious ethical issues at the clinical, managerial, and social levels. This essay focuses on the ethical issues that arise at the bedside, looking first at the ethical conflicts faced by the physician who is charged with responsibility for care of the patient and then turning to the way in which managed care exacts costs that are measured not in dollars but in compromises in the caring dimensions of the patient-physician relationship.     

Acalculia in a patient with severe language disturbances: how do we test it?

The present paper describes a case of a patient with severe Wernicke aphasia, which when tested with a number processing and calculation battery adapted to his difficulties showed remarkable arithmetic skills. These findings suggest that the patients with severe cognitive impairments (e.g., aphasia, apraxia) should be tested with batteries adapted to their disturbances because using a standard test may bias the results.