Delayed Alternation to Non-Positional Cues in Chimpanzee

Three subjects were exposed to fixed-ratio schedules of reinforcement in a two-phase experiment. In the first phase, sessions were terminated after a fixed number of responses had been emitted. In the second phase, sessions were terminated after a fixed length of time (equivalent to the mean of session lengths when steady state responding occurred in Phase 1). A comparison of response rates showed higher rates for all subjects in Phase 2.     

Varying the response code in the blindness to response-compatible stimuli

Previous work has indicated that action-control processes can specifically influence perceptual processes. The identification of a left- or right-pointing arrow is impaired when it appears during the preparation and execution of a compatible left-right keypress (Müsseler & Hommel, 1997a, b). The present study examines the role of the response-specifying cue in order to manipulate the coding of the action-control processes. Experiment 1 shows that the size of the perceptual impairment is not affected by whether the cue has high or little feature overlap with the to-be-performed response. Cues were omitted in Experiment 2 and participants generated their responses endogenously, but the perceptual impairment still occurred. Experiment 3 examines in more detail which feature of the response contributes to the effect. The results show that it needs both an intended action goal and a corresponding motor activity to bring about the perceptual impairment.     

Precuing the Target Location in Visual Searching by a Chimpanzee (Pan troglodytes): Effects of Precue Validity

A chimpanzee ( Pan troglodytes ) performed a visual search task using a modified matching-to-sample procedure in which a sample stimulus was followed by the search display, which contained one stimulus identical to the sample (target) and several uniform stimuli different from the sample (distractors). On cued trials, while the subject was observing the sample, a white square (precue) appeared at the location where the target was to be presented (valid trials), or elsewhere (invalid trials). The validity of the precue (correspondence between the cued and the target locations) was changed from 0% to 100% across conditions. Cost-benefit analyses were performed on the difference between valid and noncued trials (benefit) and between invalid and noncued trials (cost). Under the high-validity conditions, the response times were shorter when the cued location corresponded to the target location than when the precue did not appear. When the cued location did not correspond to the target location, on the other hand, the subject took longer to select the target than on noncued trials. When the validity of the precue was relatively low, however, cost of the invalid trials disappeared, while benefit of the valid trials remained. These results confirmed the two-process (automatic and attentional) theory of priming in human information processing; the advance information had the same effects on a chimpanzee's visual search performance as on humans'.     

Visual analysis of gait as a cue to identity

For humans, the ability to discriminate between, and to identify, others is paramount. The most obvious way this is accomplished is by means of face recognition. However, this is not the only method available. The present article reports on two experiments designed to see whether gait can be used as a reliable cue to identity. Experiment One showed that the human visual system was sophisticated enough to learn to identify six individuals on the basis of their gait signature under conditions of simulated daylight, simulated dusk and point‐light displays. It thus appeared that gait‐related judgements could be made, and furthermore, that these judgements were possible without reliance on shape information. Experiment Two suggested that even under adverse viewing conditions involving a single brief exposure, humans could identify a target from a ‘walking identity parade’ at greater than chance levels. These results emerged regardless of the lighting conditions, and were largely independent of the gender of the target walker. As such, the present results suggest that gait could be used as a reliable means of discriminating between individuals, and the importance of such an identity cue, in conditions in which the face is obscured, are discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

颜色对基于时间的视觉选择的影响

旨在探讨颜色属性对基于时间的图形预览搜索的影响及其机制。实验采用视觉标记实验范式的变式考察三种颜色的图形刺激的预览收益。结果发现:搜索与旧干扰物相同颜色的靶子和搜索新异颜色刺激并未出现反应时的差异,而且,两者都快于搜索与新干扰物颜色相同的靶子。这说明,在图形刺激的预览搜索中,观察者没有主动抑制旧干扰物的颜色,而是主动加工新出现的刺激。还探讨了基于颜色标记的抑制机制和主动非抑制机制。     

A Test of the Central Factor in Visual Adaptation

Bull, Nina. The Attitude Theory of Emotion. New York: Nervous and Mental Disease Monographs, 1951. Pp. 159. Reviewed by William E. Galt.     

Visual correction of a rapid goal-directed response

The purpose of this study was to investigate the role of dynamic and static visual cues in improvement of accuracy during a pointing movement. In the experiment, subjects were required to point finger rapidly at visual targets as accurately as possible. Movement amplitude was 15 cm, and movement times ranged from 100 to 190 msec. Three visual feedback conditions were applied: no feedback, dynamic ongoing feedback on the complete hand trajectory, and static error feedback on the movement end-point. Two spatial movement outcomes were considered, mean constant error and intraindividual dispersion of pointings. Data were analyzed with regard to effects of feedback and speed. Under the no-feedback condition, accuracy was lowest; constant error was not speed-dependent, whereas dispersion increased with speed of movement. Accuracy was highest under the complete feedback condition and was speed-dependent, as shown by both constant error and dispersion. Under error feedback, accuracy was intermediate and was also speed-dependent. The results are discussed in terms of the interchange between correcting mechanisms vs delayed control within the motor regulatory processes.     

对解释伪忽视机制的两种理论的初步检验

以视野因素对伪忽视的影响为切人点来考察注意的右半球优势理论与表征的空间变形理论对伪忽视机制的解释。使用灰度标尺任务和三视野速示迫选的实验方法研究视野和操作用手因素对伪忽视的影响。结果显示,只有将两种理论结合起来才能对伪忽视机制作出更好的解释。