Impossible shadows and the shadow correspondence problem

Shadows cast by objects contain potentially useful information about the location of these objects in the scene as well as their surface reflectance. However, before the visual system can use this information, it has to solve the shadow correspondence problem, that is to match the objects with their respective shadows. In the first experiment, it is shown that the estimate of the light source position is affected by a gradual luminance ramp added to the image. In the second experiment, it is shown that observers process impossible shadow images as if they ignored the local features of the objects. All together, the results suggest that the visual system solves the shadow correspondence problem by relying on a coarse representation of the scene.     

Comparing the EthoVision 2.3 system and a new computerized multitracking prototype system to measure the swimming behavior in fry fish

Coming from the framework of unmarked fry tracking, we compared the capacities, advantages, and disadvantages of two recent video tracking systems: EthoVision 2.3 and a new prototype of multitracking. The EthoVision system has proved to be impressive for tracking a fry using the detection by gray scaling. Detection by subtraction has given less accurate results. Our video multitracking system is able to detect and track more than 100 unmarked fish by gray scaling technique. It permits an analysis at the group level as well as at the individual level. The multitracking program is able to attribute a number to each fish and to follow each one for the whole duration of the track. Our system permits the analysis of the movement of each individual, even if the trajectories of two fish cross each other. This is possible thanks to the theoretical estimation of the trajectory of each fish, which can be compared with the real trajectory (analysis with feedback). However, the period of the track is limited for our system (about 1 min), whereas EthoVision is able to track for numerous hours. In spite of these limitations, these two systems allow an almost continuous automatic sampling of the movement behaviors during the track.     

A first step toward cognitive remediation of voices: a case study

Several studies have shown that source-monitoring errors are related to verbal hallucinations in schizophrenia. An exploratory pilot study has been carried out to investigate the possibility of training patients in how to avoid errors in source-monitoring. One patient with paranoid schizophrenia and persistent thought insertions was trained for 6 hours to use mnemonic techniques to compensate specific deficits in source-monitoring. Results show that the patient was able to improve his performance and maintain the acquired progress at a 1-month follow-up assessment. These preliminary results are interesting for developing a larger controlled study of cognitive remediation of source-monitoring deficits.     

Differential involvement of NMDA and AMPA receptors within the nucleus accumbens in consolidation of information necessary for place navigation and guidance strategy of mice

Recent evidence now points to a role of glutamate transmission within the nucleus accumbens (Nacc) in spatial learning and memory. Unfortunately, the role of the distinct classes of glutamate receptors within this structure in mediating the different steps of the memorization process is not clear. The aim of this study therefore was to further investigate this issue, trying to assess the involvement of the two classes of glutamate receptors within the Nacc in consolidation of spatial information using an associative spatial task, the water maze. For this purpose, focal injections of the NMDA antagonist, AP-5, and of the AMPA antagonist, DNQX, have been performed immediately after the training phase, and mice have been tested for retention 24 h later. Two different versions of the water-maze task have been used: In the place version, animals could learn the position of the platform using visual distal cues, and in the cue version, the location of the platform was indicated by a single proximal cue. The results demonstrated that posttraining NMDA receptor blockade affects mice response in the place but not in the cue water-maze task. On the contrary, AMPA receptor blockade induced no effect in either version of the task. These data confirm a functional dissociation between glutamate receptors located in the Nacc in modulating spatial memory consolidation and indicate that they are specifically involved in consolidation of information necessary to acquire a place but not to a guidance strategy.     

DECREASING DANGEROUS INFANT BEHAVIORS THROUGH PARENT INSTRUCTION

One adult and three adolescent mothers with 1-year-old infants were taught to reduce their infants' potential for injury in the home. After being taught to increase their positive interactions with their infants, the mothers were taught to child-proof the home, to use playpen time-out for potentially dangerous behaviors, and to give positive attention for safe behaviors. A multiple baseline design across subjects was used to evaluate functional control. Potentially dangerous behaviors, observed during 10 min of free play, decreased from variable and, at times, high rates during baseline to stable near-zero rates after treatment. These target behaviors remained low at a 7-month follow-up assessment.     

Performance feedback and self-focused attention in the classroom: When past and present interact

An experiment tested the impact of performance feedback on self-focused attention in high and low achievers. On the basis of previous research, which suggested that inconsistent feedback (i.e., feedback which contradicts one's performance history) receives considerable attention, it was predicted that such feedback would increase self-focus regardless of its valence (i.e., positive or negative). As predicted, high achievers were more self-focused when receiving failure feedback than when receiving success feedback or no feedback. The low achievers were more self-focused when receiving success feedback than when receiving failure feedback or no feedback. These findings are discussed in relation to Kluger and DeNisi's (1996) Feedback intervention theory and the literature on self-focused attention.     

The Influence of Social Comparison Situations on Individual Task Performance: Experimental Illustrations

In the past ten or so years, numerous experiments have been conducted to illustrate the intervention of social regulations in cognitive functioning (e.g., social coordination, sociocognitive conflict, and social marking). However, in that way, social comparison processes have not received any extended theoretical and empirical attention. Several experimental results are reported here in an attempt to show that the social conditions, in particular personal and categorical comparison situations, in which subjects are led to perform memory and problem-solving tasks constitute a determining factor in their cognitive performances. The discussion presents some new theoretical prospects for the study of social regulations of cognitive functioning.     

Typicality of Interpersonal Situations: The Role of Affect in Determining Contextual Variations in Typicality Norms

This study deals with the relationship between affect and cognition. This relationship is conceptualized in the terms of Bower's (Bower & Cohen, 1982) theory. Subjects (early adolescents aged 12 or 14, boy or girl) were asked to imagine themselves as the actor in an interpersonal situation. The situation was either intimate or non-intimate, and the hypothetical partner was either a boy or a girl. The subject's task was to produce a series of sentences expressing the behaviours considered representative of each situation. The results indicated (1) the existence of a typicality hierarchy (whose characteristics are examined here) and (2) variations in this hierarchy according to the affective tone of the situation (intimate or non-intimate). We explain how the cultural, interpersonal situation norms acquired by adolescents can account for these variations. Thus, contrary to what some authors contend, variations in typicality are not random.     

Can societal language amendments change gender representation? The case of Norway

This study investigates the influence of stereotypical information and the grammatical masculine on the representation of gender in Norwegian by applying a sentence evaluation paradigm. In this study participants had to decide whether a second sentence containing explicit information about the gender of one of more of the characters (e.g. . . . one of the women . . . ) was a sensible continuation of a first sentence introducing a role name (e.g. The spies came out . . . ). Participants' representations were biased by the stereotypicality of the role names when reading female (e.g. nurses) and male (e.g. pilots) stereotyped role names (replicating findings from the English sample in a previous publication), but male biased when reading neutral role names (replicating findings from the French and the German samples in a previous publication).