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At least 919 records · Page 51Linked to original sources
PubMed2000

[Psychological complexity of the figures and properties of retention in visual short-term memory].

We investigated how the physical variables of complex figures had effects on psychological complexity and recognition of complex figures. Complexity was objectively defined by the amount of convex parts and Perimeter/square root of Area (P/square root of A), which varied with both the number of convex parts and the length of one convex part. In complexity judgments the results showed that the judged complexity was not well predicted by P/square root of A, and that the amount of convex parts rather than P/square root of A had much influence on the judged complexity. In a recognition experiment, the results showed that performance was dependent on both the number of convex parts and the length of one convex part when P/square root of A was held constant. When P/square root of A was low and constant, performance tended to deteriorate with increasing the amount of convex parts. But when P/square root of A was high and constant, performance peaked at a convex parts value of 8, and deteriorated at higher or lower values of convex parts. The results indicated that both the number of convex parts and the length of one convex part were effective in deteriorating retention in visual short-term memory, and that P/square root of A had indirect influence on performance.

Adult↗
PubMed1989

The changing face of visual persistence.

In three experiments, the effect of target luminance on estimates of visual persistence was determined on a popular successive-field task. Even though the experiments differed from each other only in terms of minor changes in stimulus conditions, very different effects were obtained across the three experiments. The different findings were attributed to the often overlooked roles of masking and target degradation on tasks of persistence. Implications for the numerous contradictory findings in the persistence literature are discussed, and the current popularity of the successive-field task is questioned.

Afterimage↗
PubMedDate not supplied

Behavioral effects of 0 and 0.05% blood alcohol in male volunteers.

Five behavioral tests were evaluated to determine their sensitivity to the subtle central nervous system (CNS) depressant effects produced by ingestion of ethanol. Twenty-one adult male volunteers received 0 and 1.4 ml 100 proof vodka/kg body weight according to a "double-blind" crossover design. Behavioral tests were conducted between 15 and 65 minutes after ethanol ingestion, when blood alcohol concentrations (BAC's) were between 0.05 and 0.06%. Tests evaluated were Archimedes spiral, digit span memory, critical flicker fusion, stabilometry and tachistoscope. Multivariate analysis of variance (MANOVA) using composite scores representing the individual tests indicated that the battery as a whole was sensitive to ethanol effects. Repeated measures analysis of variance (ANOVA) on each test indicated that critical flicker fusion, stabilometry and tachistoscope contributed more to the overall sensitivity of the battery than did digit span memory and Archimedes spiral.

Animals↗
PubMed1985

Classification and determination of cerebral bioavailability of fluoxetine: pharmacokinetic, pharmaco-EEG, and psychometric analyses.

In a double-blind placebo-controlled cross-over study, the pharmacokinetic, encephalotropic, and psychotropic properties of fluoxetine were investigated in 8 normal volunteers. Subjects received in randomized order, at 2-week intervals, single oral doses of placebo and 30, 60, and 75 mg of fluoxetine. Data were obtained at baseline and 2, 4, 6, 8, and 10 hours after drug administration. There was a dose-dependent rise in plasma levels up to the 4th to 6th hour, followed by a slow decline, consistent with the reported long half-life. Digital computer period EEG analysis showed only mild encephalotropic effects of fluoxetine compared with placebo. The EEG changes, especially in the vigilance-controlled recordings, were similar to those seen after antidepressants of the desipramine type; changes in resting EEGs after the highest dose resembled those seen after imipramine-like drugs. Maximal CNS efficacy occurred between the 8th and 10th hours postdrug. The hysteresis between peak blood levels and maximal pharmacodynamic effects suggests formation of an active metabolite. Psychometric investigations showed behavioral changes after fluoxetine that are known to occur after the administration of antidepressants to normal subjects. The drug was well tolerated.

Adult↗
PubMed1985

The influence of adapting velocity and luminance on the movement after-effect.

The response of movement-sensitive mechanisms to both velocity and luminance may be investigated by means of the movement after-effect (MAE). A high contrast (98%) drifting grating having a spatial frequency of 1c deg-1 was used with four adapting velocities of 0.90, 2.87, 4.70 and 7.55 deg sec-1 to confirm their significant effect on initial MAE velocity (F = 29.83, P less than 0.01) and duration (F = 12.36, P less than 0.01). Four mean luminance levels of 4.5, 12.6, 42.9 and 126 cd m-2, spanning 1.5 log units of illumination, demonstrate its subtle effect on both initial MAE velocity (F = 4.11, P less than 0.01) and duration (F = 3.00, P less than 0.05). It is argued that adaptation of movement-sensitive mechanisms is more accurately reflected by the initial MAE velocity than its duration. The tracking technique which was employed, whilst accurate at low velocities, progressively underestimates the MAE velocity with increasing velocity. With a velocity of 1.2 deg sec-1 the under-estimate is 12%, rising to 23% at 2 deg sec-1. The tracking procedure, however, remains a reliable technique for assessing low velocity MAEs.

Adaptation, Ocular↗