Visual temporal integration for threshold,signal detectability,and reaction time measures

A comparison was made of temporal integration for three different response measures in a visual detection task: (1) response frequency, (2) signal detectability as measured for rating ROC curves. (3) simple reaction times (RTs). These measures were obtained on the same trials, to the same stimuli-orange (581 rim) light pulses of 50 min of visual angle fixated foveally and presented to dark-adapted Os in a monocular Maxwellian view. All three response measures showed a period of luminance-duration reciprocity (Bloch’s law), followed by a period of partial integration. The end points of luminance-duration reciprocity (critical duration) and partial integration (utilization time) were shorter for RTs than for the response frequency and signal detectability measures. Neurophysiological.implications of differences in time constants of integration for RT and psychophysical measures are discussed.     

Experiments on neophobia in wild and laboratory rats: a reevaluation.

Two experiments using food-container avoidance as an index of neophobia are reported for two strains of laboratory and one strain of wild rats. In Experiment 1 rats were fed from a single familiar container until their consumption had stabilized. Upon replacing the familiar container with a novel container, the latency of all three strains to begin feeding increased. In Experiment 2 rats were offered a choice between a familiar and a novel container containing identical food. Though there was considerable individual variation among the three strains, the wild strain was more reluctant to eat from the novel container than a hooded laboratory strain, which, in turn, was nore reluctant than an albino laboratory strain. Nonetheless, all three strains showed an initial avoidance of the novel container. It was concluded that both wild and laboratory strains are neophobic and that strain differences are ones of degree, not of kind.     

Type A behavior pattern, parental history of hypertension, and cardiovascular reactivity in college males

Two risk factors for cardiovascular disorders, parental history of hypertension and the Type A behavior pattern, were investigated concurrently with respect to cardiovascular reactivity to challenging situations. Sixty-four college males were given both the Structured Interview (SI) and Jenkins Activity Survey (JAS) for the Type A behavior pattern and a family health questionnaire to determine parental history of hypertension. The students were monitored for blood pressure (BP), heart rate (HR), and pulse transit time (PTT) response to four tasks: cold pressor, isometric handgrip exercise, a reading comprehension task, and backwards digit span. Type As based on SI classification had significantly higher HR levels across all tasks than did Type Bs, as well as higher diastolic BP levels in the cold pressor task. No main effects for Type A-B using JAS classification were found. Positive parental history students had higher HR and shorter PTT levels across all the tasks. Type A and parental history did interact in a limited way on some tasks, but the interactions were also dependent on the Type A classification used.     

The effects of essential fatty acid supplementation by efamol in hyperactive children

Thirty-one children, selected for marked inattention and overactivity, were studied in a double-blind, placebo-controlled crossover study of essential fatty acid (EFA) supplementation. Subjects received the active treatment and placebo conditions for 4 weeks each and were assessed on a variety of cognitive, motor, and standardized rating scale measures. EFA supplementation (evening primrose oil; Efamol®) resulted in significantly lower levels of palmitoleic acid (a nonessential fatty acid) and higher concentrations of dihomogammalinolenic acid, an EFA previously found to be deficient in some hyperactive children. Supplementation was also associated with significant changes on two performance tasks and with significant improvement to parent ratings on the subscales designated as Attention Problem and Motor Excess of the Revised Behavior Problem Checklist. However, a variety of eight other psychomotor performance tests and two standardized teacher rating scales failed to indicate treatment effects. When the experimentwise probability level was set at.05, only 2 of 42 variables showed treatment effects. Baseline EFA concentrations appeared to be unrelated to treatment response. It was concluded that EFA supplementation, as employed here, produces minimal or no improvements in hyperactive children selected without regard to baseline EFA concentrations.This study was supported by grants from Efamol Research Inc., and the Medical Research Council of New Zeland. We thank Messers. Patrick Flynn and Mark Norwood for carrying out the statistical analyses.     

How many memory systems? Evidence from aging

The present research tested Tulving's (1985) ternary memory theory. Young (ages 19-32) and older (ages 63-80) adults were given procedural, semantic, and episodic memory tasks. Repetition, lag, and codability were manipulated in a picture-naming task, followed by incidental memory tests. Relative to young adults, older adults exhibited lower levels of recall and recognition, but these episodic measures increased similarly as a function of lag and repetition in both age groups. No age-related deficits emerged in either semantic memory (vocabulary, latency slopes, naming errors, and tip-of-the-tongue responses) or procedural memory (repetition priming magnitude and rate of decline). In addition to the age by memory task dissociations, the manipulation of codability produced slower naming latencies and more naming errors (semantic memory), yet promoted better recall and recognition (episodic memory). Finally, a factor analysis of 11 memory measures revealed three distinct factors, providing additional support for a tripartite memory model.