Some theorems in haploscopic vision

Three formal hypotheses are specified concerning the combination of neural signals from the two eyes. The hypotheses are (1) that a large uniform light presented to the opposite eye has no effect (independence), (2) that all information from one eye relevant to a given percept (for example, brightness) is encoded by a single neural signal (isolation), and (3) the mutually exclusive and exhaustive alternative to isolation (interaction). Though independence or isolation often has been claimed or simply assumed to hold, these hypotheses imply specific empirical relationships. These relationships are derived for brightness and for equilibrium colors. In addition, one model consistent with the interaction hypothesis is developed. The isolation hypothesis is important for generalizing results from monocular experiments to normal binocular vision. If it is false, monocular results can reflect a combination of one eye's neural signals that never occurs with binocular stimuli.     

Hemispheric specialization for temporal information: Implications for the perception of voicing cues during speech perception

Developmental research reporting electrophysiological correlates of voice onset time (VOT) during speech perception is reviewed. By two months of age a right hemisphere mechanism appears which differentiates voiced from voiceless stop consonants. This mechanism was found at 4 years of age and again with adults.A new study is described which represents an attempt to determine a more specific basis for VOT perception. Auditory evoked responses (AER) were recorded over the left and right hemispheres while 16 adults attended to repetitive series of two-tone stimuli. Portions of the AERs were found to vary systematically over the two hemispheres in a manner similar to that previously reported for VOT stimuli. These findings are discussed in terms of a temporal detection mechanism which is involved in speech perception.     

Writing patterns of the congenitally neurologically impaired adult.

The writing patterns of two adults diagnosed as having congenital neurological impairment were submitted to linguistic analysis. The written work of these persons was found to contain errors incompatible with those of undereducated native speakers of English but somewhat analogous to errors of aphasics: tense, plural, and possessive endings are absent; articles and prepositions are absent or are used incorrectly; subordinating words are absent or incorrectly used. Yet the oral performance of these persons was syntactically unremarkable. It seems, therefore, that congenital neurological damage can affect the written performance while leaving the oral performance comparatively intact.     

Microinfusion of the D1 receptor antagonist, SCH23390 into the IL but not the BLA impairs consolidation of extinction of auditory fear conditioning

In auditory fear conditioning, repeated presentation of the tone in the absence of the shock leads to extinction of the acquired fear response. Both the medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA) are involved in extinction. Here we examined this involvement by antagonizing D1 receptors in both regions, in the rat. We microinfused the D1 receptor antagonist, SCH23390, into the infra-limbic part of the mPFC (IL) or BLA at different time points. SCH23390 mircoinfused into the IL either before extinction acquisition or following short extinction training resulted in impairment of extinction consolidation. Microinfusion of SCH23390 into the BLA, prior to acquisition of extinction caused impairment in acquisition of extinction without affecting extinction consolidation. This is supported by the results showing that microinfusion of SCH23390 into the BLA following a short-training session did not affect consolidation. These results further strengthen the role of mPFC in consolidation of extinction while highlighting the role of the D1 receptors in this process.     

The effects of alternatives on the salience of reward allocation norms

In a dyadic bargaining situation there is considerable evidence that the alternative outcomes of the bargainers (if they cannot reach agreement) have important effects on bargaining outcomes. Under the assumption that situational factors affect the nature of the relation between the alternatives of the bargainers and bargaining outcomes, the effects of two factors were assessed: the relative size of the reward to be negotiated (excess of prize minus alternatives) and the magnitude of the difference in the alternatives of the two bargainers. Using college students as subjects, the predictions of two models were also contrasted: the equal excess model and Shapley-w. The relative size of the prize did not have a significant effect on the accuracy of the two models, but the magnitude of the difference in alternatives had marked effects. The results also suggest that the Shapley-w model may be more accurate when the bargainers are relatively inexperienced and cooperatively oriented, whereas the equal excess model may be more accurate when the bargainers are relatively sophisticated and competitively oriented.