Activity status in psychophysiologic studies. "Changes in the general activity level in psychophysiologic studies--an analysis of objective and subjective parameters"

The general activation level (GAL) is one of the sources of influence in psychophysiological experiments. That means most of the results are dependent on the GAL. Taken this into account one can furthermore elucidate a part of the high variability of the interesting physiological data. We analysed heart rate (HR), auditory evoked potentials (AEP) elicited by background stimuli and the subjective assessment of the internal state of the subjects to describe changes of the GAL. Summarizing the results we can show different influences of the GAL on the physiological data. Changes of HR and AEP-parameters are caused by specific experimental conditions. The distinct influence of the subjective state of the subjects on the AEP-shapes allows the conclusion that subjective data should be more taken into consideration. The comprehensive characterization of the GAL requires data of different integrative levels.     

How much and how fast: rapid processing of spoken language in later adulthood

Speech processing involves rapid decoding and construction of meaning from a transitory acoustic signal. Because older adults have been found to be slower in performing many cognitive tasks, we hypothesized that they may have difficulty in immediate recall for speech of increasing input rate. Two experiments are reported in which both older and younger participants listened to and immediately recalled sentences that were systematically varied in speech rate and number of propositions. Although recall performance of the older adults showed a disproportionate decline when speech rate was increased, older adults, as well as the younger adults, were able to recall sentences of increasing propositional densities. We also found that the tendency to recall a greater proportion of main ideas than details (the levels effect) was enhanced by increased propositional density, and depressed by increased speech rate and increased age. These results are discussed in terms of an age-related change in the rate at which information can be processed in working memory.     

Changes in the general activation level in psychophysiologic studies--II. Values of auditory evoked potentials in relation to impression and perception and heart rate

In psychophysiology all procedures used are accompanied with changes of general activation level (GAL) of the subjects. In our study these changes are characterized by self-assessment of the internal state and by the mean heart rate (HR) of each period. On the basis of these data group mean auditory evoked potentials (AEPs) were computed. The influence of the GAL on the N 110- and P 190-amplitudes of the AEPs was analysed. There was no effect on the P 190-amplitude whereas the N 110-amplitude shows distinct responses on changes in GAL. These amplitudes diminished when the subjects reported a change of internal state. The diminishing of N 110-amplitudes took place as well at an increase as at a decrease of the internal state factors. Comparing the HR and the N 110 of the AEPs we found an inverse U-shaped dependence. These results are discussed in comparison to the literature. Furthermore a model which could elucidate the observed findings is presented for a critical discussion.     

Spacing repetitions over 1 week

Does varying the spacing of repetitions over intervals as long as 1 week aftect recall? The answer from three experiments is yes. Subjects incidentally processed words repeated within a single list and words repeated in separate lists at list spacings of up to 1 week. Memory was tested by free recall shortly after the second presentations or after retention intervals of up to 1 week. Recall of the words repeated across separate lists conformed to a proportionality rule. When the retention interval is short relative to the spacing intervals, performance is inversely related to spacing. When the retention interval is a large proportion of the spacing intervals, performance is directly related to spacing. Does varying the spacing of repetitions within a single list affect recall after a retention interval of 2 weeks? The answer depends on the processing used while studying the words. Processing that generated interitem associations resulted in a within-list spacing effect even after a 2-week retention interval. Without the interitem associations, the effect was absent after a 1-day retention interval. Most of these findings were explained by examining the changing relationship between the retrieval context and the context stored during study.     

Hippocampal damage and exploratory preferences in rats: memory for objects, places, and contexts

Rats have a natural tendency to spend more time exploring novel objects than familiar objects, and this preference can be used as an index of object recognition. Rats also show an exploratory preference for objects in locations where they have not previously encountered objects (an index of place memory) and for familiar objects in contexts different from those in which the objects were originally encountered (an index of context memory). In this experiment, rats with cytotoxic lesions of the hippocampal formation were tested on all three versions of the novelty-preference paradigm, with a 5-min retention interval between the familiarization and test phases. Rats with sham lesions displayed a novelty preference on all three trial types, whereas the rats with hippocampal lesions displayed a novelty preference on Object trials but did not discriminate between the objects on Place trials or Context trials. The findings indicate that hippocampal damage impairs memory for contextual or spatial aspects of an experience, whereas memory for objects that were part of the same experience are left relatively intact.     

Towers of Hanoi and London: contribution of working memory and inhibition to performance

The Tower of Hanoi and Tower of London have become well-established executive function tasks that presumably tap cognitive skills mediated by the frontal cortex. It has been assumed that the two tower tasks are more or less interchangeable and that both measure working memory and inhibition processes. These assumptions were tested in a study involving 37 normal college volunteers (M age = 20 years). Participants were administered the Tower of Hanoi (TOH), Tower of London-Revised (TOL-R), two working memory tests, and two tests of inhibition. The two tower tasks correlated significantly (r = .39), but only moderately. The working memory and inhibition variables explained over one-half of the variance in TOL-R performance; however, there was a relatively weaker contribution of inhibition to TOH performance.