The relationship between cognitive,motor-kinesthetic,and oculomotor adaptation

The literature concerning adaptation to prism indicates that several adaptive mechanisms may be important. The particular mechanism or mechanisms involved depends (at least in part) upon the type of adaptive exposure. In the present study. three adaptive mechanisms (cognitive. oculomotor, and motor-kinesthetic) were investigated. Ss were asked to point in the dark at an illuminated target. The target was seen displaced from its veridical position due to a wedge prism placed before S’s right eye. The left eye was occluded. Ss then viewed their visual target pointing errors through the displacing prism without seeing any part of their bodies. One group of Ss was instructed to ignore these prism-induced errors and to continue pointing at the target’s visual position. A second group of Ss was instructed to compensate fully for their errors and to at tempt to eliminate them on all future trials. For the latter group errors were completely eliminated, while for Ss instructed to ignore their errors, relatively small improvement in visual target settings occurred. This improvement was called cognitive adaptation, since it depended on the S’s conscious control. In addition. for both conditions. evidence was found that allowing Ss to view their prism-induced pointing errors resulted in some form of motor-kinesthetic adaptation. This adaptation was hypothesized to represent a change in the judged position of the pointing hand relative to its felt position. It was concluded that this motor-kinesthetic adaptation was dependent, in part, upon cognitive information concerning the effects of the prism and that it serves to reduce conflict between cognitive and visual cues, i.e., between what S believes and what he sees.     

Generalization of auditory intensity as a function of small amounts of discrimination training

Rats were trained on a two-valued auditory-intensity discrimination for 5, 2, 1 or 0 days. Then, the bar-press response rate was sampled in the presence of seven added discrimination stimuli (generalization) for seven days. Daily training sessions were 4 hr in length throughout the experiment. Only the five-day group exhibited a marked superiority on the multi-valued discrimination when contrasted with the group having had no prior simple discrimination training.     

Oculomotor adaptation to wedge prisms with no part of the body seen

When S looks at a visual target through prisms, adaptive shifts in reaching behavior occur even though he sees no part of his body through the prisms. These shifts are caused by a change in the judgment of the direction of gaze (oculomotor change), which in turn is caused by two secondary prismatic effects: (a) asymmetry of the visual display and (b) apparent rotation about a vertical axis of a panel or wall facing S. The “asymmetry” factor contributes 22% of the total oculomotor change, and the “rotation” effect contributes the remaining 78%. Oculomotor change is not facilitated by eye-movement activity. The adaptive oculomotor change induces a non-adaptive proprioception change about one-tenth as large as the oculomotor change. These findings are capable of accounting for the previously unexplained results reported by Wooster in 1923, and also for the current controversy about the role of reafferent stimulation in sensorymotor adaptation.     

Oculomotor adaptation to wedge prisms with no part of the body seen

When S looks at a visual target through prisms, adaptive shifts in reaching behavior occur even though he sees no part of his body through the prisms. These shifts are caused by a change in the judgment of the direction of gaze (oculomotor change), which in turn is caused by two secondary prismatic effects: (a) asymmetry of the visual display and (b) apparent rotation about a vertical axis of a panel or wall facing S. The “asymmetry” factor contributes 22% of the total oculomotor change, and the “rotation” effect contributes the remaining 78%. Oculomotor change is not facilitated by eye-movzment activity. The adaptive oculomotor change induces a non-adaptive proprioception change about one-tenth as large as the oculomotor change. These findings are capable of accounting for the previously unexplained results reported by Wooster in 1923, and also for the current controversy about the role of reafferent stimulation in sensorymotor adaptation.     

Book reviews

The Popularization of Medicine 1650–1850 Roy Porter (ed.), 1992 London, Routledge pp. x + 296, £50 (hardback) ISBN 0415 07217 4

Quantum Mechanics: An Empiricist View Bas Van Fraassen, 1991 Clarendon Press, Oxford pp. 558, £17.50 (paperback), ISBN 019 8239807     

Reference in single sentences and in texts

This study investigated the comprehension and production of reference terms in both sentences (Experiments 1 and 2) and texts (Experiments 3 and 4) using a sentence completion task. In Experiments 1 and 2, the use of a sentence-level strategy (subject assignment) was investigated. In Experiments 3 and 4, the use of a text-level strategy (topic assignment) was also investigated. There was a clear preference for continuing the sentences by referring to the subjects of the sentences regardless of the availability of gender cues, in both single sentences and in texts. There was also an influence of the topic of each text on both the choice of referent and the type of reference term used. However, the choice of reference term was affected by the number of potential antecedents in the preceding text. Overall, the results suggest that the sentence subject is a salient item in working memory. This salience is increased if the sentence subject is also the textual topic. In addition, it appears that the presence of a pronoun in a text triggers a specific strategy to assign the pronoun to the (salient) sentence subject.This work is based on a doctoral dissertation submitted by R. A. Crawley to the University of Durham and supported by the Medical Research Council of Great Britain.     

The use of heuristic strategies in the interpretation of pronouns

The aim of the two experiments reported here was to distinguish between two heuristic strategies that have been proposed to account for the assignment of pronouns: the subject assignment strategy and the parallel function strategy. According to the subject assignment strategy, a pronoun is assigned to a preceding subject noun phrase, whereas according to the parallel function strategy, a pronoun is assigned to a previous noun phrase in the same grammatical position as the pronoun. These two strategies were tested by examining the interpretation of single object pronouns, first in a reading task and second in an assignment task. In both experiments, there was a strong preference for assigning an object pronoun to the preceding subject noun phrase, thus supporting the subject assignment strategy. However, this was only the case for pronouns that were linguistically ambiguous. When assignment was constrained by gender, there was no effect of either strategy. It is suggested that heuristic strategies are only used in the absence of other strong cues to assignment.     

The “good manager”: Sex-typed,androgynous, or likable?

Recent studies have indicated that people describe a “good manager” in masculine terms. It was hypothesized that this could simply reflect cultural stereotypes, rather than people's perceptions of what combination of traits is desirable in a leader. In Experiments 1 and 2, subjects were presented managerial profiles ascribing all masculine, all feminine, or a combination of masculine and feminine traits (i.e., “androgynous” profiles) to hypothetical managers. Feminine-trait combinations were rated as significantly less desirable than either masculine or androgynous combinations, which were rated as equally desirable. Thus, while femininity per se was not seen as desirable in a leader, it was not viewed as a liability when combined with masculinity, a corroboration of much behavioral research on androgyny. Experiment 3 varied trait likableness and sex-role orientation. Experiments 1 and 2 were replicated for unlikable traits. Surprisingly, the opposite pattern was obtained for likable traits: the feminine combinations were rated as the most desirable, and the masculine combinations were rated as the least desirable. The results are discussed in the context of early research on impression formation and recent work on social cognition.