On the Functional Role of Implicit Visual Memory for the Adaptive Deployment of Attention Across Scenes

Although very little visual information is explicitly retained across views, some continuity of processing is afforded by implicit visual memory traces of previous views. These memory traces interact with attentional mechanisms to guide eye movements, cognition, and action. Two different memory mechanisms are described here. First, the deployments of focal attention and eye movements are facilitated towards recently attended features and locations (priming of popout). Second, attention is guided by implicit memory traces of specific visual contexts experienced in the past (contextual cueing). Compared to the visual memory tapped by change blindness tasks, the implicit memory mechanisms of priming of popout and contextual cueing do not require conscious intervention and may exhibit greater memory capacity, longer durability, and higher discriminability. Thus, these implicit traces of past views guide attention and eye movements to allow for effective access (indexing) to a scene's details, hence providing context and continuity to ongoing interactions with the perceptual world.     

Role of conditioned reinforcers in the initiation,maintenance and extinction of drug-seeking behavior

The development of a secondary reinforcer as a result of associating a neutral stimulus (buzzer) with intravenous (IV) doses of morphine was studied in rats. Secondary reinforcement developed in the absence of physical dependence and followed the association of the stimulus with either response-contingent or non-contingent injections of morphine. Strength of the conditioned reinforcer, measured in terms of responding on a lever for the stimulus plus infusion of saline solution, was proportional to the unit dosage of morphine employed in pairings of buzzer and drug. When extinction of the lever-press response for IV morphine was conducted (by substituting saline for morphine solution) in the absence of the conditioned reinforcing stimulus, it was seen later that the stimulus could still elicit lever responses, until it too had been present for a sufficient interval of non-reinforced responding. Similarly, extinction of the response for morphine by blocking its action with naloxone in the absence of the stimulus did not eliminate the conditioned reinforcement. Another study showed that a passive, subcutaneous (SC) dose of morphine served to maintain lever-pressing on a contingency of buzzer plus sahne infusion. Furthermore, the stimuli resulting from the presence of morphine (after a SC injection) were able to reinstate the lever-responding with only the buzzer-saline contingency when such responses had previously been extinguished. Moreover, it was shown thatd-amphetamine could restore responding under the same conditions, and that morphine could also do so for rats in which the primary reinforcer had beend-amphetamine. It is suggested that animal data such as these show that procedures designed for the elimination of human drug-taking behavior must take into account secondary reinforcers as well as the primary reinforcer(s).     

The effect of an integration program on teacher and student attitudes to mentally-handicapped children

This study examines the effect of contact with autistic children on teacher and peer attitudes to mentally-handicapped children in general. Children were interviewed and teachers completed questionnaires about their attitudes toward mentally-handicapped children in five schools attended by autistic boys and five schools not attended by any mentally-handicapped children. Children who had contact with autistic boys had more positive and realistic attitudes. Teachers' attitudes were generally positive and did not vary across settings, but those with experience in teaching mentally-handicapped children were found to have more positive attitudes than those with no experience. The implications for the integration of mentally-handicapped children are briefly discussed.