A counterchange mechanism for the perception of motion

A computational model for the perception of counterchange-specified motion is examined in detail and compared with various versions of the Reichardt motion detection model [Reichardt, W. (1961). Autocorrelation, a principle for the evaluation of sensory information by the central nervous system. In W. A. Rosenblith (Ed.), Sensory communication (pp. 303-317). New York: Wiley]. The counterchange model is composed of a pair of temporally biphasic subunits at two retinal locations, one detecting decreases and the other increases in input activation. Motion is signaled when both subunits are simultaneously excited, as determined by the multiplicative combination of their transient responses. In contrast with the Reichardt detector, which effectively tracks motion energy and accounts solely for results obtained with standard apparent motion stimuli (a surface is visible at one location, then at another), the counterchange model also accounts for the generalized apparent motion perceived between pairs of simultaneously visible surfaces. This indicates that standard apparent motion can be perceived via the same non-sequential, non-motion-energy mechanism as generalized apparent motion. There is no need for either an explicit delay mechanism to account for optimal motion perception at non-zero inter-stimulus intervals, or for inhibitory interaction between subunits to account for the absence of motion in the detector’s null direction (Barlow, H. B., & Levick, W. R., 1965). Both are emergent properties that result from the inhibitory states of the counterchange detector’s biphasic subunits. In addition to apparent motion, the counterchange principle potentially accounts for the perception of motion for drifting gratings, the short range motion perceived for random-dot cinematograms, and the motion perceived for continuously moving objects.     

A Dynamic Neural Field Model of Visual Working Memory and Change Detection

ABSTRACT— Efficient visually guided behavior depends on the ability to form, retain, and compare visual representations for objects that may be separated in space and time. This ability relies on a short-term form of memory known as visual working memory. Although a considerable body of research has begun to shed light on the neurocognitive systems subserving this form of memory, few theories have addressed these processes in an integrated, neurally plausible framework. We describe a layered neural architecture that implements encoding and maintenance, and links these processes to a plausible comparison process. In addition, the model makes the novel prediction that change detection will be enhanced when metrically similar features are remembered. Results from experiments probing memory for color and for orientation were consistent with this novel prediction. These findings place strong constraints on models addressing the nature of visual working memory and its underlying mechanisms.     

The usual and the unusual suspects: level of suspicion and counter-interrogation tactics

The present study investigated guilty mock-suspects' counter-interrogation tactics with respect to the disclosure of possibly self-incriminating information, specifically, to what extent the disclosure of this information was moderated by (1) the suspects' criminal experience (naïve versus experienced) and (2) the degree of suspicion directed towards the suspects (low versus high). We found that experienced (versus naïve) suspects volunteered less self-incriminating information in an initial free recall phase. In a similar vein, when asked crime-specific questions, naïve (versus experienced) suspects admitted having committed more actions fitting with the crime under investigation. Furthermore, experienced suspects' willingness to report information was not affected by the degree of suspicion, whereas naïve suspects in a high-suspicion (versus low-suspicion) condition were more willing to report information. The results were discussed in the light of the psychology of guilt, the Strategic Use of Evidence technique for detecting deception, and the (over)use of naïve suspects as mock-suspects in psycho-legal research. Copyright © 2009 John Wiley & Sons, Ltd.     

Brief owner absence does not induce negative judgement bias in pet dogs

Humans in a negative emotional state are more likely to judge ambiguous stimuli as negative. In recent years, similar judgement biases have been found in some non-human animals that were exposed to long-term or short-term treatments aimed at influencing their affective states. Here we tested pet dogs in the presence and absence of their owners in a judgement bias test with an established go/no-go procedure. Even though owner absence is thought to induce a state of anxiety in dogs that have formed an attachment bond with their primary caretakers, we found no difference between the dogs' responses to ambiguous stimuli in the presence or absence of their owners. This result may be explained by the absence of anxiety in dogs that are accustomed to brief periods of separation from their owners, or by a sensitivity limit of the customary judgement bias tests in non-human animals when only a moderate, short-term state of anxiety is induced. In addition, we found significant differences between individuals and populations in the responses to ambiguous stimuli, which give impetus for further research.     

Physical activity interventions in the school setting: A systematic review

Objectives

To review the effectiveness of school-based interventions with a physical activity component by measuring changes in psychological determinants, physical activity, and health outcomes.

Design

Systematic Review.

Method

We conducted a literature search of school-based controlled studies that involved a physical activity intervention targeting school students. Study design, methodological quality, and effectiveness of interventions on three target levels, ‘health and fitness’ (BMI and motor performance), ‘physical activity’, and ‘psychological determinants’ (knowledge of physical activity effects, self-concept, and attitudes towards physical activity), were analysed. Furthermore, we examined the influence of specific factors (e.g., age and gender) and mediator effects.

Results

The literature search identified 129 studies. The majority of the studies examining motor performance, physical activity, and knowledge of physical activity achieved significant results (69.7%, 56.8% and 87.5%, respectively). Significant effects on self-concept and attitudes were also found but to a smaller extent (in 30% and 43.8% of the studies, respectively). Only a few studies examining BMI (2.7%), physical activity (6.8%), and attitudes towards physical activity (12.5%) revealed negative effects, with better results observed for the control group. Intervention effects were influenced by the students’ age, intervention type, and frequency of the interventions. Self-efficacy was found to mediate the relationship between the program and the students’ physical activity.

Conclusions

Numerous school-based physical activity interventions achieved positive effects on three target levels. Further research is needed to clarify the mediator effects of psychological variables on physical activity and health and to increase our knowledge about the mechanisms that underlie behavioural change.     

Categorical-relational and order-relational information in memory for subject-performed and experimenter-performed actions

Memory for self-performed tasks (SPTs) is better than memory for experimenter-performed tasks (EPTs). In short unrelated lists of actions this effect occurs if the encoding condition is manipulated within subjects. In a between-subjects design, the enactment effect disappears (J. Engelkamp & D. Dehn, 2000; J. Engelkamp & H. D. Zimmer, 1997). These findings were explained by the item-order hypothesis, which claims that encoding order information depends on the type of encoding and design. The authors demonstrate that this differential encoding of order information in EPTs and SPTs is not effective in free recall if categorized lists are used. The use of categorized lists makes the interaction of type of encoding and design in free recall of short lists disappear, and the enactment effect reappears independent of the type of design.     

Wie kann man in der Sozialtherapie Therapieerfolg feststellen oder messen?

The tradition of social therapeutic evaluation research in Germany is as old as the institution of social therapy itself. Social therapeutic facilities constitute the royal road to correctional treatment in the German prison system providing an integrated approach for offender treatment by means of psychotherapy (mainly cognitive-behavioral), vocational and job training, social work and leisure time therapy embedded in a therapeutic community. It was generally expected that evaluation research would prove the effectiveness of this method and generate results for the advancement of offender treatment. However, research results have yielded only moderate findings concerning the effects of social therapeutic interventions. This article considers how the outcome of social therapy and offender treatment is measured. Fundamental methodological challenges that evaluation research has to face are identified. In addition, a short overview of recent results from a longitudinal evaluation study is presented to substantiate the dilemmas and solutions of evaluation research in this field. It is discussed why it is so difficult to provide evidence for effectiveness of correctional treatment and concluded that this can by no means lead to a renunciation of the correctional treatment approach.