Orienting responses as a function of age and task complexity.

Aged-related differences in the elicitation and habituation of orienting responses to the onset and offset of stimuli have been suggested by several authors. Electrodermal and cardiac orienting responses to the onset and offset of a visual stimulus were measured in three age groups (4 yr., 7 yr., and undergraduate). Each S made one of three judgments: non-signal (observe stimulus), content (color of stimulus), and duration (length of time stimulus presented). Few age differences were found in elicitation or habituation of orienting responses to stimulus onset or offset. There was a trend for elicitation of orienting responses to stimulus offset to be age-related, but the failure to find any other age-related changes made this difference somewhat questionable. Instructions as to the judgement to be made by S were the primary determinants of orienting responses to stimulus onset and offset across all age groups.     

Handedness as a function of sex and age in a large population of Lemur

A population of 194 lemurs (Lemur spp.), 116 males and 78 females, from 1 to 30 years of age, was assessed for lateralized hand use in simple food reaching with a minimum of 100 reaches per animal. A hand preference was present in 80% of the population with a bias for use of the left hand that was most characteristic of male lemurs and young lemurs. The results confirm the presence of lateralization in prosimians, and we interpret the sex and age differences in relation to current theories of neural lateralization.     

Handedness and immune function

Geschwind, Galaburda, and Behan (GBG) have suggested that in utero levels of testosterone influence both cerebral and immune system developments (Geschwind and Behan, 1982; Geschwind and Galaburda, 1984; Geschwind and Galaburda, 1985). According to this theory, high levels of testosterone result in greater incidences of left-handedness, deviations from standard distribution of cerebral functions (known as anomalous dominance), and increased autoimmune dysfunction. While the original data supported these assertions, more recent tests of the hypothesis have been equivocal. One criticism of these studies is that the definition of both handedness and anomalous dominance are too vague. It was one of the aims of this project to investigate and clarify the GBG model by examining four different aspects of handedness as well as a more direct measure of anomalous dominance. In order to extend the GBG model, degree of left-handedness, general immune system functioning, and current testosterone levels were also examined. First, it was predicted and found that left handers had a higher incidence of autoimmune diseases in their immediate families than did right handers. Second, those left handers with an incidence of at least one autoimmune disease were more strongly left-handed than were those with no incidence of autoimmunity. Finally, it was observed that higher testos terone levels were supportive of general immunity. The present findings both support and expand the GBG model.     

Memory for orientation of forms as a function of their meaningfulness and complexity.

Accuracy of memory for left-right orientation of single figures varying in meaningfulness and complexity was studied in subjects from kindergarten to adulthood. Complexity was an unimportant variable. Orientation of meaningful figures was remembered better than orientation of nonmeaningful figures at all ages. There were no developmental differences in memory for meaningful figures beyond kindergarten, but pronounced developmental differences were found in memory for nonmeaningful figures. It was proposed that a decision to store orientation information is dependent upon a judgment about the meaningfulness of a presented figure, and that young children have more difficulty than adults in finding meaningfulness in unfamiliar forms. The decision to store appears to occur automatically, since there was only a small difference between conditions in which subjects were informed or not informed to remember orientation. It was also suggested that part of the often reported difficulty in remembering diagonal orientation may be due to the symmetry of the diagonal forms typically investigated.     

Correlational cuing as a function of target complexity and target-flanker similarity

It is generally assumed that the correlational cuing effect (CE) between targets and correlated flankers is due to learning association between the flankers and their correlated responses. The present study challenges this view. Experiment 1 shows that the CE for targets composed of color is eliminated as soon as the correlation is removed. Experiment 2 shows that the CE during training is not due to association of the flankers with responses. Experiment 3 shows that at least some of the CE during training with the correlation is due to repetition priming of the display. Experiment 4 replicates the results of Experiment 1 for orientation targets. In Experiments 5-7, more typical tasks with letter targets are examined, and it is demonstrated that preexperimental similarity between targets and correlated flankers is crucial. The CE for correlated but dissimilar target-flanker pairs, similar to that for color and orientation targets, is confined to on-line processes that occur during training. The CE is transferred, however, for correlated and similar target-flanker pairs. We propose that, at least for the simple stimulus to response mapping used in our study, the CE is not due to learning at all. Instead it is due to (1) on-line processes, such as repetition priming, that occur during training with the correlation and (2) a regular flanker effect (see, e.g., B. A. Eriksen & C. W. Eriksen, 1974) that occurs for similar target-flanker pairs.     

Dual-task performance as a function of adult age and task complexity

A dual-task procedure was used to examine capacity demands of letter-matching in younger and older adults. Older subjects generally were slower on both tasks than were younger adults, but this difference was especially pronounced for the late stages of category matching, suggesting that retrieval and comparison of category information is particularly demanding for older adults.     

Regression weights as a function of test length

A battery of pencil-and-paper tests is commonly used for predicting a single criterion. If the score on each test is the number of correct answers, the composite battery score would normally be the sum of the weighted test scores, where the weights are the raw score regression weights. Knowing the reliability of each test, it is possible to alter the lengths of the tests in a manner such that the weights will all be equal. The composite battery score would then simply be the total number of items answered correctly and scoring would be greatly simplified. Such simplification is particularly desirable where the volume of testing is large. Section I of the article outlines the procedure for altering the lengths of the tests, and Section II gives a proof of the method.     

Self-reported arousal Factorial complexity as a function of the subject's arousal level

Abstract.— The factorial stability of a previously constructed six-factor check-list for self-reported arousal was studied in three different situations which were conceived of as inducing different levels of arousal, viz. in the evening before going to bed, at a lecture, and at an examination. The analyses showed that the six factors obtained in the Lecture group were reduced to five in the Examination group and to four in the Evening group. This reduction was due to a combination of the items from pairs of the original factors into one factor. Significant differences between the three groups were obtained in all factors but one. The results were regarded as support for the usefulness of the six-factor instrument, the implication being that one or two of the factors in some situations might be redundant. The relevance of the results for a previously proposed model of arousal was discussed.     

Children's preference for complexity as a function of perceived units in collative motivation

The purpose of this investigation was to manipulate a constant number of four elements (red and blue rectangles) to represent differentially perceived units of complexity. The hypothesis that motivational arousal and choice preferences of second- and fifth-grade children would be a positive function of the number of perceived units, ranging from one to four, was confirmed, consistent with Berlyne's (1960) theory. When the number of elements was held constant at three, as compared to four, similar results were obtained in a test at two intermediate levels of complexity. Implications for organization of elements and the effects of symmetry in determining children's preferences for levels of complexity are discussed.     

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.     

Information search and choice accuracy as a function of task complexity and task structure

Previous research has consistently shown that subjects switch to noncompensatory information search behaviour when task complexity increases. However, a rather specific class of tasks was used in these studies for which complete information search is not necessary to attain accurate task performance. In the present study information search behaviour, choice accuracy, subjective difficulty and confidence were registered under various task complexity conditions in two different task environments. In the first task, subjects had to make a choice between apartments; in the second task, a choice was required between baskets containing groceries of different prices. Forty subjects made choices by means of computerized information boards. The results showed effects of both complexity and type of task on information search behaviour. The lowest proportion of requested information and the most variable search pattern was observed for the apartments task in the complex task condition. However, accuracy remained constant over all complexity conditions. Together, the results suggest that under high task complexity levels subjects try to work smarter rather than harder. In the context of a choice requirement the specific task structure may allow them to switch to noncompensatory strategies while maintaining accuracy and avoiding the integration of large amounts of information.     

Simple reaction time as a function of response complexity: memory drum theory revisited

The prediction emanating from memory drum theory (Henry & Rogers, 1960') that simple reaction time (SRT) increases as a response becomes more complex (i.e., increases in number of movement parts) was investigated. Experiments 1 (N = 20) and 3 (N = 16) indicated that SRT was longer for responses consisting of two and three parts than it was for a one-part response and this may be interpreted as support for the prediction. Failing to support the prediction, however, was the finding that SRT was essentially the same for responses consisting of two and three parts. This may not be too damaging to the theory because it could simply be reflecting an upper limit in terms of numbers of parts or response duration for causing an increase in SRT. Experiments 2 (N = 20) and 3 revealed an SRT effect between two responses that were supposed to be equal in complexity. At first, this finding appeared to be contrary to the prediction, but it may be interpreted as support for it because one of the responses defined as having one movement part could actually have had two