Normalized pulse volume and blood volume as separate indices of finger arterial and venous vascular tone: Examination under propofol

Abstract: This study examined the newly proposed indices for estimating finger vascular tone, which can be obtained from near infrared transmittance photoplethysmographic recordings; normalized pulse volume (NPV) and blood volume (BV). They were recorded for seven male and two female students under continuous infusion of and recovery from propofol. Concomitant hemodynamic measurements were made with a non-invasive impedance cardiograph and a continuous blood pressure monitor. Normalized pulse volume showed no apparent dose-dependency and was negatively correlated with total peripheral resistance. In contrast, BV increased dose-dependently with propofol concentration and was negatively correlated with cardiac preload index (PLI) and with stroke volume (SV) at higher concentrations. The supplementary structural equation modeling procedure effectively illustrated causal relationships between BV, PLI and SV. In conclusion, the present data suggest that NPV and BV independently reflect arterial and venous tone in the finger tip, respectively. Although the underlying mechanisms remain unclear, BV is more sensitive to vascular dilation under propofol anesthesia.     

Attention demands of movements as a function of their duration and velocity

The attention demands of initiating and controlling discrete movements were examined as a function of their movement time (MT) and average movement velocity. Experiment 1 showed that the attention required to execute a movement decreased as MT decreased, although Experiment 2 through independently manipulating MT and movement velocity, revealed that movement velocity is the key determiner of attention demands rather than MT. The attention demands of preparing a high velocity movement are greater than during its execution with the reverse being the case for relatively slow velocity movements. The results are compatible with the view that it is the initiation of error corrections that are attention demanding (Keele 1973).     

Endogenous visuospatial precuing effects as a function of age and task demands

This experiment examined the effects of age on processing resource capacity using an endogenous visuospatial precuing task and four levels of resource demands. Younger and older adults made speeded two-choice responses to dim and bright targets that required a line-orientation or a lexical decision. An arrow preceding target onset served as an attentional cue to affect the spatial distribution of resources. It provided accurate information about the target’s location on most trials and inaccurate or neutral information on the remaining trials. Although older adults were slower than younger adults under all conditions and were more affected by the resource demand manipulations, they exhibited a pattern of precuing effects across conditions that was similar to that of the younger adults. Results are consistent with the idea that the visuospatial attention system remains relatively unaffected by aging. However, the data speak against the idea that capacity reduction is the primary contributor to age-related slowing.     

Pulmonary function as a cause of cognitive aging

Human aging is associated with decline in cognitive and physical functioning. Although pulmonary function predicts long-term performance (up to 10 years) on measures of cognitive function, recent data suggest the opposite relationship: Cognitive decline predicts self-reported physical limitations. In the study reported here, we utilized dual-change-score models to determine the directional relationship between pulmonary and cognitive function. Our sample consisted of 832 participants (ages 50-85 years at baseline), who were assessed in up to seven waves of testing across 19 years as part of the longitudinal Swedish Adoption/Twin Study of Aging. Changes in pulmonary function led to subsequent changes in fluid cognitive function, specifically, in tasks reflecting psychomotor speed and spatial abilities. There was no evidence that declines in cognitive function led to subsequent declines in pulmonary function. Thus, these data indicate a directional relationship from decreased pulmonary function to decreased cognitive function, a finding that underscores the importance of maintaining pulmonary function to ensure cognitive performance.     

Individual differences in religiosity as a function of cognitive ability and cognitive style

The current study examines the degree to which individual differences in cognitive ability and cognitive style (rational thinking vs. experiential thinking) uniquely and jointly account for differences in religiosity. Using an array of measures of religiosity, results show that cognitive ability has a medium to large negative effect on various aspects of religiosity. Though also negatively related to religiosity, rational thinking style did not add significant unique effects, nor did it convey a significant indirect effect from cognitive ability. Experiential thinking was generally unrelated to ability but was positively related to some aspects of religiosity. Overall the results confirm that those with higher cognitive ability are less likely to accept religious doctrine or engage in religious behaviors and those with lower ability are more likely to accept religious doctrine and exhibit higher levels of fundamentalism. Cognitive style appears to play a lesser role in explaining individual differences in religiosity than cognitive ability.     

Hemispheric asymmetries for global and local processing as a function of stimulus exposure duration

The experiments assess the relationship between stimulus exposure duration and hemispheric asymmetries for global and local processing. Six durations (27, 40, 53, 67, 80, and 147 ms) were tested in a selective attention task in which hierarchical letterforms were presented unilaterally to the left or right visual field. The results indicated that left hemisphere-local asymmetries were demonstrated more often than right hemisphere-global asymmetries and that asymmetries were most commonly found in the middle range of durations tested. The pattern of results emphasizes the importance of further study into those conditions under which the predicted asymmetries can be reliably demonstrated in healthy individuals.     

Inter-hemispheric recruitment as a function of task complexity,age and cognitive reserve

In a behavioral divided visual field study, we investigated the efficiency of inter-hemispheric cooperation according to (1) task computational complexity (physical-identity versus name-identity letter matching), (2) age (younger versus older adults) and (3) educational attainment, used as a proxy for cognitive reserve. Overall, the results indicated a shift from within- to across-hemisphere processing advantage with increasing task complexity, suggesting that bilateral engagement leads to enhanced performance under high-demand conditions. This pattern was influenced by age, with older adults showing no within-hemisphere advantage in the simpler task and a greater across-hemisphere advantage in the more complex one, consistent with an age-compensatory view of inter-hemispheric recruitment. Moreover, for older adults, more years of education was associated with a weaker across-hemisphere advantage. Thus, we propose that cognitive reserve may account for bilateral engagement efficiency. Finally, the groups differed in terms of laterality effects, with only younger adults demonstrating a left visual field advantage in the name-identity task, lending some support to the right hemi-aging hypothesis.     

Grammatical number elicits SNARC and MARC effects as a function of task demands

Despite the robustness of the spatial–numerical association of response codes (SNARC) and linguistic markedness of response codes (MARC) effect, the mechanisms that underlie these effects are still under debate. In this paper, we investigate the extraction of quantity information from German number words and nouns inflected for singular and plural using two alternative forced choice paradigms. These paradigms are applied to different tasks to investigate how access to quantity representation is modulated by task demands. In Experiment 1, we replicated previous SNARC findings for number words—that is, a relative left-hand advantage for words denoting small numbers and a right-hand advantage for words denoting large numbers in semantic tasks (parity decision and quantity comparison). No SNARC effect was obtained for surface or lexical processing tasks (font categorization and lexical decision). In Experiment 2, we found that German words inflected for singular had a relative left-hand advantage, and German words inflected for plural a relative right-hand advantage, showing a SNARC-like effect for grammatical number. The effect interfered, however, with a MARC-like effect based on the markedness asymmetry of singulars and plurals. These two effects appear to be dissociated by response latency rather than task demands, with MARC being more pronounced in early responses and SNARC being more pronounced in late responses. The present findings shed light on the relationship of conceptual number and grammatical number and constrain current accounts of the SNARC and MARC effects.     

Test anxiety,working memory,and cognitive performance: Supportive effects of sequential demands

Substantial evidence suggests that test anxiety is associated with poor performance in complex tasks. Based on the differentiation of coordinative and sequential demands on working memory (Mayr & Kliegl, 1993), two studies examined the effects of sequential demands on the relationship between test anxiety and cognitive performance. Both studies found that high sequential demands had beneficial effects on the speed and accuracy of the performance of test-anxious participants. It is suggested that the more frequent memory updates associated with high sequential demands may represent external processing aids that compensate for the restricted memory capacity of individuals with high test anxiety.     

Bending perception to desire: Effects of task demands,motivation, and cognitive resources

Determinants of motivated judgments were examined in this research. Three experiments investigated how dominant motivation, biasing difficulty and mental resources combine to produce motivationally congruent judgments. Studies 1 and 2 showed that where a biasing motivation is dominant the presence of resources can augment a motivational bias in judgment. Study 3 replicated that result and showed that resources contribute to the formation of biased judgments only where biasing is difficult to accomplish, but not where it is relatively easy to accomplish. In addition, Study 3 showed that where the accuracy motivation is dominant and biasing is the easy default, unbiased judgments will occur only in the presence (vs. absence) of resources. In contrast, where unbiased judgments are easy to come by, such judgments occur irrespective of resources.     

Reduction of cognitive dissonance as a function of magnitude of dissonance,differentiation, and self-esteem

The purpose of the present experiment was to test several hypotheses concerning the interrelationship of dissonance reduction mechanisms in a situation where response possibilities are relatively unconstrained. Engaged female students were invited to take part in a bogus ?Marriage Expectancy Test' that was supposed to allow predictions of marriage success. One week later, they received fictitious results differing negatively from their initial expectations of marriage success. The reactions measured were ?conformity with the result' and ?derogation of source' (confrontation mechanisms), and ?devaluation of importance of the issue' and ?under-recall' (avoidance mechanisms). As predicted, avoidance responses increased steeply with discrepancy, while little increase was found for confrontation mechanisms. Psychological differentiation had no significant effect on dissonance reduction, whereas high vs. low self-esteem influenced ?derogation of source' and ?devaluation of importance of the issue'.     

Age-related cognitive decline as a function of daytime testing

The current study investigates the effects of age, cognitive load, optimal time-of-day testing, and irrelevant background noise suppression on mental processing. One hundred and seventy-eight young (M = 22.97 years) and 114 old adults (M = 56.38 years) were assessed for implicit learning and speed of information processing under irrelevant sound interference early during daytime (7AM–2.30PM) or in the afternoons (3PM–midnight). No direct effect of irrelevant speech effect was found on implicit learning. An optimal time of testing per age group was identified according to the ability to suppress irrelevant auditory information. If no semantic meaning was derived from the sound conditions, irrelevant sound was easily inhibited leaving no room for declined cognitive performance. This suggests an intact phonological inhibition in older adults and a further circumvention of the phonological loop. However, when difficulty was increased, a widened performance gap between young and old people could be observed. Education modulated difficult performance irrespective of age. With increasing age, task demand fulfillment becomes a function of a limited time mechanism. If extraneous time is not adapted to cognitive skills and performance, higher order processing cannot be reached, rendering older adults slower than their younger counterparts.     

Dual-task interference as a function of cognitive processing load

Sixteen subjects from the Naval Submarine Medical Research Laboratory participated in a dual-task study designed to measure processing requirements of a choice reaction time (RT) task. Two levels of choice RT stimulus-response (S-R)compatibility were tested with each of two tracking tasks to provide different levels of dual-task loading. In one tracking task, the target's temporal-spatial pattern was fixed; in the other, the target's path was a function of the subject's performance. In the choice RT task, compatibility was treated as a between-subjects factor, while the number of alternatives (set size) within a sequence was a within-subjects variable. Choice RT results indicated that compatibility and set size interacted; the increase in response latency as a function of set size was much greater when compatibility was low. An increase in choice RT response latency occurred when the secondary tracking task was added. Within a given compatibility level, this dual-task decrement was constant for all levels of set size; however, the magnitude of the dual-task decrement varied as a function of S-R compatibility, being greater when compatibility was low than when it was high. For these data, a model like Sternberg's (1969) stages model is seen to have more explanatory value than a pooled processing capacity model (e.g., Norman and Bobrow 1975).