Attentional enhancement during multiple-object tracking

What is the role of attention in multiple-object tracking? Does attention enhance target representations, suppress distractor representations, or both? It is difficult to ask this question in a purely behavioral paradigm without altering the very attentional allocation one is trying to measure. In the present study, we used event-related potentials to examine the early visual evoked responses to task-irrelevant probes without requiring an additional detection task. Subjects tracked two targets among four moving distractors and four stationary distractors. Brief probes were flashed on targets, moving distractors, stationary distractors, or empty space. We obtained a significant enhancement of the visually evoked P1 and N1 components (～100–150 msec) for probes on targets, relative to distractors. Furthermore, good trackers showed larger differences between target and distractor probes than did poor trackers. These results provide evidence of early attentional enhancement of tracked target items and also provide a novel approach to measuring attentional allocation during tracking.     

Discrimination of acoustic communication signals by grasshoppers (Chorthippus biguttulus): temporal resolution, temporal integration, and the impact of intrinsic noise

A characteristic feature of hearing systems is their ability to resolve both fast and subtle amplitude modulations of acoustic signals. This applies also to grasshoppers, which for mate identification rely mainly on the characteristic temporal patterns of their communication signals. Usually the signals arriving at a receiver are contaminated by various kinds of noise. In addition to extrinsic noise, intrinsic noise caused by stochastic processes within the nervous system contributes to making signal recognition a difficult task. The authors asked to what degree intrinsic noise affects temporal resolution and, particularly, the discrimination of similar acoustic signals. This study aims at exploring the neuronal basis for sexual selection, which depends on exploiting subtle differences between basically similar signals. Applying a metric, by which the similarities of spike trains can be assessed, the authors investigated how well the communication signals of different individuals of the same species could be discriminated and correctly classified based on the responses of auditory neurons. This spike train metric yields clues to the optimal temporal resolution with which spike trains should be evaluated.     

How to Exploit Diversity for Scientific Gain: Using Individual Differences to Constrain Cognitive Theory

ABSTRACT— People often show considerable systematic variability in their ability to perform many different cognitive tasks. In this article, we argue that by combining an individual-differences approach with an experimental-cognitive-neuroscience approach one can often further constrain potential theories of the underlying cognitive mechanisms. In support of this proposal, we outline three basic benefits of using an individual-differences approach: validating neurophysiological measures, demonstrating associations among constructs, and demonstrating dissociations among apparently similar constructs. To illustrate these points, we describe recent work by us and other researchers that utilizes each of these techniques to address specific questions within the domain of visual working memory. It is our hope that some of these techniques for utilizing individual variability may be applied to other domains within cognitive neuroscience.     

Why do the effects of delaying reinforcement in animals and delaying feedback in humans differ? A working-memory analysis

Animal research has shown that reinforcement is substantially less effective when it is delayed, but in studies of human motor learning delays in providing feedback typically have much less effect. One possible explanation is that in human research participants know the response to be learned and can thus focus on it during the delay; that is not the case in experiments on animals. We tested this hypothesis using a task in which participants had minimal information on what movement was correct and found that, as in animal experiments, participants learned only when feedback was immediate. A second experiment confirmed that the effects of the delay depended on how many responses had to be held in working memory: the greater the memory load, the poorer the learning. The results point to the importance of activity during a delay on learning; implications for the teaching of motor skills are discussed.     

Biased Assimilation and Attitude Polarization in Response to Learning About Biological Explanations of Homosexuality

According to attribution theory stigmatized behaviors with biological explanations will be perceived more positively than those with psychological explanations, but informing people of the biological explanations of homosexuality has produced mixed results on attitudes. To examine if biased processing could explain previous findings we tested whether biased assimilation (initial attitudes’ effect on perceived persuasiveness) and attitude polarization (initial attitudes’ effect on reported attitude change) affected learning about biological explanations of homosexuality among 210 U.S. undergraduates. General Linear Model analyses showed that (1) individuals with positive attitudes toward homosexuality saw biological explanations as a more persuasive reason to accept homosexuality than those with negative attitudes, and (2) initial attitudes generally led to a strengthening of those attitudes after learning about biological explanations.     

Bulimia nervosa in undergraduate women: Factors associated with internalization of the sociocultural standard of thinness

Diverse areas of research and theory are integrated in an attempt to better understand the specific risk factors for bulimia nervosa identified in the literature. It is suspected that the interplay of risk factors may be unique to different groups of individuals who develop bulimia. Further, it is proposed that specific determinants be studied individually to determine their particular influence in the etiology of bulimia. It is suggested that the investigation of specific risk factors for bulimia in certain groups will benefit researchers and clinicians in gaining a better conceptual understanding of the process involved in the development of the disorder. This article focuses on the determinants of a specific risk factor (i.e., internalization of the sociocultural standard of thinness) for bulimia in undergraduate women, a group identified as particularly vulnerable to this disorder. Research and theory are integrated to suggest that a combination of specific individual differences, family, and social factors make some undergraduate women more vulnerable to the influence of the sociocultural standard of thinness and bulimia. Suggestions for the inclusion of these psychosocial factors in future empirical investigations and treatment programs are also discussed.     

Bemerkingen zur Ausfagentheorie des radikalen Phyfikalismus

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