The response ratio hypothesis for magnitude estimation

Assume that each presentation of a signal produces two independent random variable representations and that the ratio of responses on successive trials of a magnitude estimation experiment are proportional to the ratio of a representation from the present trial, which representation is then lost, to the remaining one from the previous trial. The mean response to a particular signal depends on the mean of the representation used, but in general exhibits drift over trials and sequential effects due to the preceeding trial; the mean response ratio does not exhibit drift, but it has a simple form only when there are no sequential effects; however, a modified mean ratio function has a simple form. A model suggested by D. V. Cross is a special case of this one. Simple timing and counting models for the representations fail to exhibit sequential effects, contrary to considerable data. However, data of the authors have suggested a version of the timing model in which the sample size of the representation varies by an order of magnitude depending on how close the signal is to the preceding one; this hypothesis accounts for the observed sequential effects and other aspects of the data.     

Fixed and optional stopping models for two-choice discrimination times

Several current models for choice- or discrimination-time experiments represent the stimulus as a sequence of independent and identically distributed observations. This paper develops and compares models based on two different stopping rules that a subject might use to terminate his sampling process and convert his perceptual evidence into an observable response. The fixed and optional stopping rules yield different predicted forms for the speed/accuracy tradeoff function and for the relation between mean and variance of response times. These predictions are developed in the general case and then specialized for certain conditions of symmetry, so that the expressions are easier to apply and to compare between models. A later section considers how changes in stopping criteria (either between or within experimental trials) affect predictions about mean response times for correct responses and errors, and then uses these ideas to relate the optional stopping rule for the Random Walk models to those of the Accumulator models. A final section considers specialized models for stimulus detection and intensity discrimination that assume Poisson-distributed sensory input, and relates these models to the present fixed stopping model.     

The psychology of farming: A review of twenty-five years of research

If all of mankind is to have an adequate diet, we must both stabilize world population and increase markedly world food supply. Moreover, attaining any such increase in food supply may be as much a problem in vocational psychology (e.g. the skill, knowledge, openness to change, and motivation of farmers) as in agricultural technology. The purpose of this review is to further psychological work on agricultural productivity by listing and evaluating a cross-section of relevant articles since 1945. Because psychologists have largely ignored agriculture, most reviewed studies were conducted by other behavioral scientists. Studies are grouped according to three broad areas: (1) predictors of choice, success, and satisfaction; (2) adoption of recommended practices; and (3) communal agriculture.     

A behaviorally-based measure of manifest needs in work settings

This investigation represents an attempt to develop and validate a research instrument (Manifest Needs Questionnaire) capable of measuring the four needs of achievement, affiliation, autonomy, and dominance using behaviorally-based scales. The instrument is designed to measure such needs with specific reference to work settings and with minimal time requirements for completion. Results of both laboratory and field studies among 640 subjects indicate that the instrument exhibits acceptable levels of convergent, discriminant, and predictive validity, as well as reasonably high test-retest reliability and internal consistency. Results are compared to other, lengthier instruments designed to measure similar needs.     

Age trends in children's time-sharing performance

To investigate developmental differences in time-sharing performance, 60 boys, 20 in each of three age groups (7-, 10-, and 13-year-olds) performed an auditory matching task and a tracking task alone and concurrently, the latter under two sets of instructions. Decrements produced by concurrent performance were compared for the three age groups. When the time-shared tasks were presented as equally important, time-sharing produced significantly greater proportional decrements in the tracking performance of the younger children and for all age groups tracking task decrements were directly related to matching task difficulty. Subsequently, the children were instructed that one or the other of the tasks was more important and that they were to improve their performance on that task. All three age groups showed a significant improvement on the task emphasized by instructions. The relationship of the results to two models of information processing is discussed.     

Evaluating socioeconomic status bias in the WISC-R

The use of intelligence tests in making special education placement decisions for children has come under repeated scrutiny in recent years. Arguments for and against the use of IQs have centered around the issue of test bias. In California a permanent moratorium on the use of intelligence tests in placing minority group children into classes for the educable retarded has been handed down by the court. One defense proposed by advocates of mental testing has been that the tests are biased against socially and economically disadvantaged groups irrespective of race. According to Clarizio (1978), if a test predicts equally well for two groups it can not legitimately be described as biased. The purpose of this investigation was to evaluate the test bias of the Verbal IQ as measured by the Wechsler Intelligence Scale for Children-Revised in relation to predictions of academic achievement in two different socioeconomic status groups. The results indicated that Verbal IQs are not biased with respect to socioeconomic status. Derived regression equations are presented along with an analysis to inspect the statistical power of the original tests.     

Longitudinal neuropsychological report of aphasia following left-subcortical hemorrhage

The neuropsychological assessments of a patient with language disturbance following left thalamic-putaminal hemorrhage over a $\text{2}\text{1}\text{2}\text{-}\text{year}$ period are presented together with premorbid measures of performance. Findings indicate that behavioral deficits which are both linguistic and nonlinguistic in nature differ from cortical aphasic syndromes in symptomatology and recovery course. The deficit pattern is also unlike that in other reported cases of left-subcortical lesions. Persistent dysarthria with fluent speech, limitation of verbal span and repetition, agraphia and anomia, and disturbances in self-regulation of behavior were noted, in addition to recovery of an initially severe auditory comprehension deficit. A distinguishing feature of this case was the relative preservation of reading comprehension in all four assessments.     

The effects of dynamic assessment procedures on Raven Matrices performance,visual search behavior,test anxiety and test orientation

The effects of dynamic testing procedures on Raven Coloured Matrices performance, visual scanning procedures, test anxiety, and orientation to the test situation were assessed. The subjects were 72 third-grade children. The results supported the hypotheses of the study showing that (1) dynamic assessment procedures involving either verbalization or elaborated feedback lead to higher levels of Raven Matrices performance; that (2) dynamic assessment modifies visual search behaviors; and that (3) dynamic assessment reduces test anxiety and negative orientation to the testing situation. The results are interpreted as offering construct validation to the assessment approaches used.