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.     

Vocalization-at-presentation and immediate recall, with varying presentation-rates

An experiment is reported in which the subject read visually presented lists with four different degrees of vocalization; immediately after reading each list he was required to reproduce it either aloud or in writing. Each list consisted of eight consonants and presentation rates were varied between I and 4 letters per sec. For any given series of lists, the subject was asked either to read the letters silently, or to mouth them silently, or to whisper them, or to say them aloud while reading.

At the fastest presentation-rate immediate recall improved monotonically with the degree of vocalization during reading of the lists; at slower rates this generalization held less well, especially for the lower degrees of vocalization. Vocalization was most helpful at the highest presentation-rate.

The overall amount correctly recalled was better for more slowly presented lists and for written as opposed to spoken recall. Analysis of the errors suggested that acoustic confusions were affected by the conditions of presentation; and that serial order intrusions were independent of presentation-or recall-conditions. An apparent variation of transpositions with voicing-and-recall-method failed to reach statistical significance. Theoretical implications of the experiment are discussed, including reference to Broadbent's theory of short-term memory (1958).     

Relations between source amnesia and frontal lobe functioning in older adults

A study is reported in which the relations among normal aging, source amnesia, and frontal lobe functioning were explored. Twenty-four older adults (aged 60-84 years) were tested on their ability to remember where they had acquired new factual information; they were also given the Wisconsin Card Sorting Test (WCST), a test of verbal fluency, and other psychometric tests. The degree of source amnesia in this normal sample correlated with age, verbal fluency, and some measures from the WCST. Source amnesia was not related to Performance IQ, however, or to a measure of fact recall. The implications for the relations among aging, memory, and frontal lobe functions are discussed.     

Critical flicker fusion in normal elderly subjects; a cross-sectional community study

Critical Flicker Fusion Thresholds (CFFTs) were measured in 644 elderly people identified from community-based general practice records, and the relationship of CFFT with age was investigated. The CFFT was measured using the method of limits with mean scores for three ascending (flicker/fusion) and three descending (fusion/flicker) presentations being recorded. The difference between the ascending and descending means was found to be significantly correlated with age (r=−0.131,P<0.001) and may reflect a reduced sensitivity of the Central Nervous System to suprathreshold flicker with increasing age. The results suggest that CFFT measurement has an important role to play in gerontological research as an objective measure of cognitive aspects of the ageing process.     

Agricultural policy and strategic investment in information technology

In this article the perspective shifts to the “upstream” end of the agricultural knowledge and information system (AKIS). Because knowledge policy and strategic decision-making are not the prerogative of the public sector, organizations such as cooperative unions and multinational companies are included. After considering the influence of the changing environment on the nature of the AKIS, the role of knowledge management and policy in the emerging knowledge and information market is examined. Special attention is given to public and private R&D. The article then looks where information technology (IT) fits in and what considerations determine strategic investment in IT projects and sustained services. Some of the European experiences with this strategic investment are evaluated.