Integration of verbal and visual information as evidenced by distortions in picture memory.

Subjects were presented with a series of pictures, some of which were general (girl walking down the path) and others specific (girl hiking down the path). These pictures were matched with sentences which were either general or specific ("The girl is walking [hiking] down the path.") Subsequently, a forced-choice picture recognition test was administered in which subjects saw pairs of pictures and indicated which member of each pair they had seen before. It was found that labelling the picture with a sentence containing a specific verb substantially increased the likelihood that the specific picture corresponding to that verb would subsequently be falsely recognized. The results are discussed in terms of current theories of memorial representation.     

The role of central and peripheral vision in perceiving the direction of self-motion.

Three experiments were performed to examine the role that central and peripheral vision play in the perception of the direction of translational self-motion, or heading, from optical flow. When the focus of radial outflow was in central vision, heading accuracy was slightly higher with central circular displays (10 degrees-25 degrees diameter) than with peripheral annular displays (40 degrees diameter), indicating that central vision is somewhat more sensitive to this information. Performance dropped rapidly as the eccentricity of the focus of outflow increased, indicating that the periphery does not accurately extract radial flow patterns. Together with recent research on vection and postural adjustments, these results contradict the peripheral dominance hypothesis that peripheral vision is specialized for perception of self-motion. We propose a functional sensitivity hypothesis--that self-motion is perceived on the basis of optical information rather than the retinal locus of stimulation, but that central and peripheral vision are differentially sensitive to the information characteristic of each retinal region.     

Studies in olfactory acuity: III. relative detectability of n-aliphatic acetates by the rat

The ability of black and albino rats to detect the first seven n-aliphatic acetates in the vapour phase has been investigated by use of an odour choice box. Both the median threshold and the slope of the probit regression line (which describes the relation between concentration and response) tend to decrease logarithmically in value as the series is ascended. The position of methyl acetate in these relations appears anomalous. When expressed as thermodynamic activities median thresholds for acetates of intermediate chain length are about equally stimulating, whilst short chain alcohols excite at decreasing activities with increasing chain length. The close similarity of these findings to those reported in the previous study on n-aliphatic alcohols supports the view that such relations may be of more general occurrence in olfaction in the rat.

The stimulus-response curve for each acetate studied shows one or more reversals in slope. It is suggested that certain of these are due to the presence of two or more olfactory receptor types one or more of which attain maximum response at lower concentrations of a given acetate than do the remainder. The asymptotes of the curves are reached in about 2-3 log units of concentration.     

Activation of midbrain structures by associative novelty and the formation of explicit memory in humans

Recent evidence suggests a close functional relationship between memory formation in the hippocampus and dopaminergic neuromodulation originating in the ventral tegmental area and medial substantia nigra of the midbrain. Here we report midbrain activation in two functional MRI studies of visual memory in healthy young adults. In the first study, participants distinguished between familiar and novel configurations of pairs of items which had been studied together by either learning the location or the identity of the items. In the second study, participants studied words by either rating the words' pleasantness or counting syllables. The ventral tegmental area and medial substantia nigra showed increased activation by associative novelty (first study) and subsequent free recall performance (second study). In both studies, this activation accompanied hippocampal activation, but was unaffected by the study task. Thus midbrain regions seem to participate selectively in hippocampus-dependent processes of associative novelty and explicit memory formation, but appear to be unaffected by other task-relevant aspects.     

Studies in the Psycho-Physiology of Transfer: III. Bilateral Practice Effects in Normal and Mirror Writing

Thirty-six children who had participated in two separate preschool studies of play interests were given an interest questionnaire when in elementary school. Sex differences in interests were studied with both age groups, with both sexes showing more varied interests in elementary school than they had in preschool. There was a significant correlation between preschool and elementary school masculinity-feminity scores for boys but not for girls. The implications of the broadening of interest patterns for both sexes and the lack of significant sex role correlations for girls were discussed in terms of changing sex role standards.     

Similarities in the physiological bases of an abnormal grooming behavior in thyroidectomized cats and in cats with lesions of the central nervous system.

Thyroidectomized cats display a dissociation of the appetitive and consummatory components of grooming behavior when the body surface is tactually stimulated, an abnormal behavior that also occurs in cats with pontile or frontal neocortical lesions. Systemic administration of 5-hydroxytryptophan (5-HTP) abolishes the abnormal behavior, whereas dihydroxyphenylalanine administration does not, and p-chlorophenylalanine (PCPA) administration induces the abnormal grooming behavior in thyroidectomized cats that are not displaying the abnormal behavior because of spontaneous seasonal reversions. Microinjections of 5-HTP or serotonin into the superior colliculi also abolish the abnormal grooming behavior in thyroidectomized cats. Lesions of the superior colliculi prevent the development of the abnormal behavior after thyroidectomy, even with PCPA treatment. These pharmacological results in thyroidectomized cats parallel the behavioral effects observed in cats with pontile or frontal neocortical lesions.     

Localization of tactile stimuli and body parts in space: two dissociated perceptual experiences revealed by a lack of constancy in the presence of position sense and motor activity

Two motor acts were analyzed at the level of tongue and fingers. These motor acts generated illusions. When subjects voluntarily rotated the tongue by 90 degrees, the perceived orientation of a tactile stimulus applied to the tongue did not covary with the perceived orientation of the tongue itself. Analogously, when subjects voluntarily crossed two adjacent fingers, the perceived position of two tactile stimuli applied to the fingers did not covary with the perceived position of the fingers themselves. Although tongue and fingers were positioned accurately in space, a lack of perceptual constancy occurred for tactile stimuli applied to these body parts. Therefore, whereas position sense was preserved, correct localization of objects was lost. The occurrence of this perceptual dissociation suggests that spatial localization of tactile stimuli may be independent both of knowledge of body part location and motor activity.     

Neurotransmitter receptors involved in post-training memory processing by the amygdala, medial septum, and hippocampus of the rat.

Rats were trained and tested in habituation to a novel environment and step-down inhibitory avoidance. Immediately after training in each task the animals received intra-amygdala, intraseptal, or intrahippocampal micro-injections of agonists and antagonists of various neurotransmitter receptors. In the habitation task, intrahippocampal, but not intra-amygdala or intraseptal administration of the NMDA receptor antagonist aminophosphornopentanoic acid (AP5, 5.0 micrograms) or of the muscarinic receptor antagonist, scopolamine (2.0 micrograms) caused amnesia and the indirect antagonist of GABA-A receptors, picrotoxin (0.08 microgram), caused retrograde facilitation. Intrahippocampal administration of the respective agonists, glutamate, oxotremorine, and muscimol, had effects of their own opposite to those of the blockers, and norepinephrine (0.3 microgram) caused memory facilitation. In the avoidance task, results obtained with drug infusions given into the three structures were very similar: in all cases, AP5, scopolamine, and muscimol were amnestic, and glutamate, oxotremorine, norepinephrine, and picrotoxin caused memory facilitation. In addition, also in the three structures, picrotoxin counteracted the amnestic effect of AP5 and/or scopolamine and the beta-adrenoceptor blocker, timolol (0.3 microgram), while ineffective on its own, attenuated all the effects of picrotoxin. The results suggest that similar synaptic mechanisms in the amygdala, medial septum, and hippocampus are involved in memory consolidation: NMDA, muscarinic, and beta-noradrenergic receptors stimulate and GABA-A receptors inhibit this process, and beta-noradrenergic receptors modulate the GABAergic synapses. In the avoidance task these mechanisms operate in the three structures: in habituation only those in the hippocampus are operative. Possibly in each structure these mechanisms regulate, if not actually consolidate, a different aspect, component, or form of memory.     

Policy conflict and policy change as a function of task characteristics III. The effects of the distribution of the validities of the cues in the conflict task

Abstract.— The effects of the distribution of the validities of the cues in the conflict task on policy conflict, as studied in Hammond's "lens model" interpersonal conflict paradigm, was investigated in a 2 (levels of task predictability) by 2 (levels of cue validity distribution: only one cue valid vs. two equally valid cues) factorial experiment. The results showed that the level of agreement was higher when only one cue was valid than when both cues were valid, but this effect was obtained only when task predictability was high. In the low predictability condition, there were no differences between the two levels of cue validity distribution. In agreement with earlier findings, the results also showed that agreement was a positive function of the predictability of the task. These results show that, to understand policy conflict, it is not sufficient to analyse only the characteristics of the parties to the conflict; it is also necessary to analyse the characteristics of the task facing the parties.