From body shadows to bodily attention: Automatic orienting of tactile attention driven by cast shadows

Body shadows orient attention to the body-part casting the shadow. We have investigated the automaticity of this phenomenon, by addressing its time-course and its resistance to contextual manipulations. When targets were tactile stimuli at the hands (Exp.1) or visual stimuli near the body-shadow (Exp.2), cueing effects emerged regardless of the delay between shadow and target onset (100, 600, 1200, 2400 ms). This suggests a fast and sustained attention orienting to body-shadows, that involves both the space occupied by shadows (extra-personal space) and the space the shadow refers to (own body). When target type became unpredictable (tactile or visual), shadow-cueing effects remained robust only for tactile targets, as visual stimuli showed no overall reliable effects, regardless of whether they occurred near the shadow (Exp.3) or near the body (Exp.4). We conclude that mandatory attention shifts triggered by body-shadows are limited to tactile targets and, instead, are less automatic for visual stimuli.     

运动视觉信息中时间知觉线索的实验研究

用两个实验考察在运动物体的时间知觉中影响ＴＴＣ判断的因素。     

珠心算训练儿童加法心算的ERP早成分研究

采用事件相关电位(ERP)的方法,对32名儿童进行了双位数加法心算实验,探讨了珠心算训练方式对儿童加法心算加工早期感知觉的影响。研究结果表明,与非珠心算训练儿童相比,在加法心算过程的早期阶段,珠心算训练儿童枕部P1、额中央区的N1波幅增大,而颞枕区N170以及额中央区P2波幅减小。本研究结果发现珠心算训练对儿童心算过程的早期感知有显著影响。     

Duration comparison: relative stimulus differences stimulus age, and stimulus predictiveness.

Under a psychophysical trials procedure, pigeons were presented with a red light of one duration followed by a green light of a second duration. Eight geometrically spaced base durations were paired with one of four shorter and four longer durations as the alternate member of a duration pair, with different pairs randomly intermixed. One choice was reinforced if red had lasted longer than green, and a second choice was reinforced if green had lasted longer. Performance was compared when all the base durations and their pair members were included (entire-range condition) or when only the four longest base durations and their comparison durations (restricted-range condition) were used. Discrimination sensitivity decreased for longer duration pairs under both conditions, supporting a memory-based account. Sensitivity was lower under the restricted-range condition. Under both conditions, a bias to report "green as longer" increased as the second green duration increased. Bias changed as a matching function of the green-duration predictiveness of the correct choice. The results are related to a quantitative model of timing and remembering proposed by Staddon.     

An empirical look at the Defence Mechanism Test (DMT) Stimulus effects

Based on a sample of non-clinical subjects (N=74) the study examines the Defence Mechanism Test (DMT) by focusing on when perceptual distortions, called ‘signs of defence’ in DMT terminology, occur (distribution in exposure duration), which part of the picture is involved (distribution in localisation), and which ‘signs’ go together (using correlation and factor analyses). The results disclosed that the occurrence of perceptual distortions (‘signs of defence’) was related to exposure duration (some ‘defences’ are more frequent at brief exposures, some others at longer exposure durations), and to localisation on the picture. The location of misperceptions to the central person (hero) or the peripheral person (pp) of the picture was the major explanatory principle for the distribution of ‘signs’ on factors. Rather than capturing psychodynamic defence mechanisms, which is the theoretical basis of the test, the analyses imply that the DMT seems to measure misperceptions which are a function of the localisation of persons on the stimulus picture and of exposure durations.     

Depression,self-focus,and social interaction

The accuracy of depressed and nondepressed subjects' perceptions of their own and a social interactional partner's performance was investigated. Twenty depressed and twenty nondepressed college students participated in dyadic interactions and then rated their own and their partner's social behavior. The interactions were also rated by objective coders. Depressed subjects were differentiated from nondepressed subjects on several measures by both the coders and the subjects. Depressed subjects' self-ratings were correlated with the coders' ratings more often than were the nondepressives' ratings, suggesting depressives provided more accurate self-observations. Contrary to prediction, depressives were also more accurate in judging their partner's behavior. Depressives experienced heightened levels of self-focused attention, but this attentional focus did not mediate the relationship between depression level and self-accuracy. Finally, an analysis of the verbal statements suggests that performance differences between depressives and nondepressives may be a function of the quantity, rather than the quality, of the verbal production.     

Cognitive components in risk perception: Natural versus manmade risks

In a questionnaire study 106 Norwegian students rated natural and manmade hazards according to risk magnitude and public versus private responsibility for risk management. Another group of 50 subjects judged 36 natural hazards on nine risk dimensions used in previous psychometric studies of ‘manmade risks’. When ratings on nine risk characteristics for natural hazards were factor analyzed a three-dimensional solution was found, with one active/passive dimension, one potency dimension, and one novelty dimension. This contrasts with the two-dimensional solution found for manmade hazards. Responsibility for risk management was found to be related to the type of risk in focus, and different risk characteristics seem to play different roles for manmade and natural hazards.     

Evaluating performance in continuous experiments with feedback to subjects

Consider an experiment in which a subject guesses repeatedly at a randomly chosen target on a continuum. To guarantee a positive probability of success, the continuum is partitioned into a finite but large number of segments. The subject is given directional feedback. General guessing strategies are characterized, and an optimal strategy is identified. The hypothesis that the subject's performance can be explained by chance alone is of interest in such experiments. A test is developed based on comparing the subject's performance to expected performance using the optimal strategy. A skill-scoring procedure is developed for assessing a subject's performance in light of the strategy used, and a test based on skill-scoring is advanced.Research by the first author is supported in part by the Air Force Office of Scientific Research under grant AFOSR 77-3180.The authors wish to thank the referees for remarks that led to improvements in both content and clarity.