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The present experiment utilized a habituation paradigm to investigate age differences in sweat gland counts (SGC), skin conductance responses (SCR), and skin conductance levels (SCL). The 12 young subjects (mean age 25.3 yrs) and the 12 old subjects (mean age 69.5 yrs) exhibited no reliable age differences in habituation of the SCR or in the magnitude of the SCRs measured. Bilateral conductance recordings revealed no laterality effects for SCR or SCL in either age group. Age differences were found for both SGC and SCL. Correlations of SGC with SCL revealed a strong relationship in the young (r = .74) and a relatively weak correspondence in the elderly (r = .22). The reverse was observed for SGC and SCR correlations, with the old sample showing consistently high correlations and the younger sample consistently low correlations. A stepwise multiple regression analysis showed that the variance in SCL predicted by age was not independent of the variance predicted by differences in SGC. The data are discussed in terms of age-related change in peripheral factors which affect electrodermal behavior. [ABSTRACT FROM AUTHOR]

Electrophysiologic potentials (average evoked potentials (AEP) and contingent negative variation (CNV)) recorded during simple recognition and discriminative responses to tachistoscopically presented letter-pair stimuli showed a systematic shift toward greater overall positivity (i.e., smaller CNVs and larger late positive components) during increased processing load. In addition, more positive P2 components were found in the fight as compared to the left hemisphere during simple recognition, and this asymmetry was enhanced during the more complex processing condition. [ABSTRACT FROM AUTHOR]

The topographic distribution of the amplitudes of the contingent negative variation (CNV) recorded along the midline at the anterior, central, and posterior regions of the human scalp varied as a function of type of information processing demanded. A parietal-dominant CNV was found when active problem-solving behavior was required. A central-dominant CNV was evident in a disjunctive reaction time task. The results are interpreted as evidence supporting a model of cortical function which predicts shifts in cortical involvement as a function of type of task demands. A late positive component (LPC) of the average evoked potential was also found to vary as a function of stage of learning, recording sites, and an attitudinal dimension measured by Rotter's internal-external locus of control scale. [ABSTRACT FROM AUTHOR]

Tests the theory that reaction time (RT) may be related to variations in blood pressure which occur with each heart beat. Absence of a relationship between RT and the phase within the cardiac cycle when stimulation occurred.

The association between a-blocking and improved reaction times (RTs) has not been consistently demonstrated in past studies. The possible importance of the preparatory interval (PT) in this relationship has not been totally assessed, and it was felt that further exploration of this variable would help to explain the discrepancies. RTs were measured in two experiments, each using different types of stimuli and different P1 durations. In the first, 4 PIs, 0.5-, 3.0-, 6.0-, and 15.0-see, were used in a regular and irregular series. The warning signal was a 400-cps tone; the stimulus, a 1000-eps tone. In the second, PIs were 0.50-, 0.75-, 1.00-, and 1.50-sec; the stimulus was a single flash from a photo stimulator. EEGs were recorded simultaneously from the parietooccipital region. Both peak-to-peak amplitude measures and subjective ratings of a-activity were made prior to the onset of the warning signal and the stimulus. The results did not support earlier findings of a relationship between a-blocking and RT. How- ever, RT and a-blocking were each (independently) a function of the P1. [ABSTRACT FROM AUTHOR]

The CNV was measured from 5 female and 5 male Ss during a pitch discrimination task with two levels of difficulty. It was found that females had larger CNVs during easy trials titan during difficult trials. They also had larger CNVs for difficult trials in which they made incorrect judgments than for difficult trials in which they made correct judgments. The effect of difficulty and of correctness on the CNV is interpreted as a distraction phenomenon. [ABSTRACT FROM AUTHOR]