Detection performance in pop-out tasks: nonmonotonic changes with display size and eccentricity

We carried out three experiments to investigate detection performance in pop-out tasks and analysed how performance varied as a function of display size (number of elements) and retinal eccentricity of the target. Results showed that when display size was increased from 2 to 81 elements performance first decreased and then increased (replicating Sagi and Julesz, 1987 Spatial Vision 2 39-49). Performance variations differed as a function of eccentricity and often were more pronounced in the periphery than in the foveal area. This retinal-eccentricity influence suggests that processes underlying detection performance in small display sizes are different from those in large display sizes. One should be careful when using the variation of display size as an instrument to analyse visual-search processes because this analysis could be based on a comparison between non-equivalent conditions.     

Illusory 3-D rotation induced by dynamic image shading

Observers' perceptions of the three-dimensional structure of smoothly curved surfaces defined by patterns of image shading were investigated under varying conditions of illumination. In five experiments, observers judged the global orientation and the motion of the simulated surfaces from both static and dynamic patterns of image shading. We found that perceptual performance was more accurate with static than with dynamic displays. Dynamic displays evoked systematic biases in perceptual performance when the surface and the illumination source were simulated as rotating in opposite directions. In these conditions, the surface was incorrectly perceived as rotating in the same direction as the illumination source. Conversely, the orientation of the simulated surfaces was perceived correctly when the frames making up the apparent-motion sequences of the dynamic displays were presented as static images. In Experiment 6, moreover, the results obtained with the computer-generated displays were replicated with solid objects.     

Are changes in beliefs and attitudes about sleep related to sleep improvements in the treatment of insomnia?

Dysfunctional beliefs and attitudes about sleep are presumed to play an important mediating role in perpetuating insomnia. The present study evaluated the impact of cognitive-behavioral and pharmacological treatments for insomnia on sleep-related beliefs and attitudes and the relationship between those changes and sleep improvements. The participants were older adults with chronic and primary insomnia. They received cognitive-behavior therapy (CBT), pharmacotherapy (PCT), combined CBT+PCT (COMB), or a medication placebo (PLA). In addition to daily sleep diaries and sleep laboratory measures, the participants completed the dysfunctional beliefs and attitudes about sleep scale (DBAS) at baseline and posttreatment, and at 3-, 12- and 24-month follow-up assessments. The results showed that CBT and COMB treatments produced greater improvements of beliefs and attitudes about sleep at posttreatment than PCT and PLA. Reductions of DBAS scores were significantly correlated with improvements of sleep efficiency as measured by daily sleep diaries and by polysomnography. In addition, more adaptive beliefs and attitudes about sleep at posttreatment were associated with better maintenance of sleep improvements at follow-ups. These findings highlight the importance of targeting sleep-related beliefs and attitudes in the treatment of insomnia.     

Selective impairment of lexical stress assignment in an Italian-speaking aphasic patient

Psycholinguistic speech production models assume that lexical stress is stored and accessed separately during phonological encoding. We address the questions of the storage and computation of lexical stress in a case study of an Italian-speaking patient with an impairment of lexical stress assignment in naming, reading, and repeating single words. The patient's stress error pattern and his performance on tasks examining lexical stress in perception suggest an impairment in the retrieval of the stress pattern of irregular words. In contrast, his assignment of stress to nonstored phonological forms suggests that the computation of stress is unimpaired.     

Perception of pictorial eye gaze by baboons (Papio papio)

Pictorial faces looking left or right were presented to baboons (Papio papio) before the display of a target letter in the left or right hemifield of a monitor screen. Baboons had to provide go or no-go responses taking into account the identity of the target letter. The 1st 6 experiments showed no reliable effect of eye gaze on discrimination speed, using either schematic gazes or pictures of real gazes. Experiment 7 showed that eye gazes facilitated target processing when eye cues were perfect predictors of target location. Findings suggest that baboons do not spontaneously process eye-gaze direction but can learn to do so if the gaze has a predictive value. Implications of these findings on baboons' perspective-taking abilities are discussed.     

Division of the corpus callosum into subregions

Various attempts have been made to subdivide the corpus callosum (CC) into anatomically and functionally distinct subareas. A promising current approach is the use of factor analytic techniques in conjunction with traced MRI images. The traced images are divided into 99 percentile slices, where the widths of the percentile slices are used as variables that are entered into the analysis (Denenberg, Kertesz & Cowell, 1991). Studies that use this technique agree broadly between 6 and 7 factors, but available factor solutions contain inconsistencies and large gaps, which arise when many of the percentile slices do not load appreciably on any of the factors. The present study uses a larger number of brains (N = 184), all normalized, and some methodological refinements in the analysis of the traced MRI images of the CC. A stable 7 factor solution was found, and the factor structure for males and females was very similar.     

Acquired equivalence and distinctiveness of cues: I. Exploring a neural network approach

Rats were placed in 4 contexts (A, B, C, D) where they received 2 auditory stimuli (X, Y); in A and B, presentations of X were paired with food and those of Y were not, and in C and D, Y was paired with food and X was not. Rats then received combinations of contexts that had provided congruent (AB, CD) or incongruent (AD, CB) information about X and Y's relationship to food. Responding was more variable during congruent than incongruent trials (Experiment 1) and was systematically increased and decreased during congruent (relative to incongruent) trials by the presentation of food or no food, respectively (Experiment 2). These results support a connectionist approach to acquired changes in stimulus distinctiveness.     

Unrealistic optimism and perceived control: role of personal competence

This work analyzed the effects of unrealistic optimism in the interaction between the emotional valence of future events, the perception of control over these events, and the person with whom one compares oneself. It was hypothesized that, if the person of comparison is judged as very competent, a pessimistic bias should be produced. Likelihood of four different types of events (positive and controllable, positive and uncontrollable, negative and controllable, and negative and uncontrollable) were rated by 133 university students (22 men and 111 women) for themselves, for an average student, for their best friend, and for a bright friend. A pessimistic bias was observed on the relative likelihood of the events when the comparison was made between oneself and a competent and bright friend, when events were perceived as controllable, especially positive ones. Not enough is known, however, to provide meaningful interpretation at present; that must await further data and theoretical development.     

Repeatability of mae-geri-keage in traditional karate: a three-dimensional analysis with black-belt karateka

In karate, performance also depends on a correct body shape, and the repeatability of standardized movements conditions the effectiveness of techniques. The execution of mae-geri-keage (frontal snap kick) was studied in 13 karateka (1st-5th dan). The 3D trajectories of 13 body landmarks were analyzed by an optoelectronic instrument while each karateka performed 10 repetitions of the movement. For each karateka and repetition, the standard deviations of the spatial coordinates x, y, z for each landmark were computed. A total standard deviation of the single participant was also calculated. Two experienced karateka performed with the best repeatability (smaller standard deviation) while executing the studied kick. Generally, the best repeatability was observed in the horizontal plane. The lower variability was observed in hips and head. Ankle and knee of the dominant limb had the worse. The method could detect athletes particularly gifted for the discipline. Moreover, it could help in the identification of those parts of body that do not repeat the movement with the desired precision.