A general scheme for the analytic decomposition of objective test scores: Illustrative demonstrations using the Rod-and-Frame test and the Müller-Lyer illusion

Objective tests of personality typically include a number of items or trials; the total score on the test is the sum of the subject's “correct” responses across all such trials. Normally, the trials are varied systematically across various facets of the test design, so that the total score represents a composite measure of accuracy averaged across these test facets. However, since only one score is computed for each subject, some potentially important kinds of individual differences—namely all those associated with each particular variation in the test design—are treated solely as measurement unreliability. Such a psychometric stance may serve to obscure more differentiated types of individual differences, with the result that composite scores from trials based on one type of experimental design may not be highly related to such scores from trials using a somewhat different design. The present paper presents a general procedure for scoring objective tests more analytically. To illustrate this general rationale, and to demonstrate its potential utility, data have been reanalyzed from two previous studies, one using the Rod-and-Frame test, the other the Müller-Lyer illusion. In both cases, the traditional global accuracy score did not correlate significantly with other theoretically related variables, while a number of component scores were quite highly related.     

The form of analog size information in memory

The information used to choose the larger of two objects from memory was investigated in two experiments that compared the effects of a number of variables on the performance of subjects who either were instructed to use imagery in the comparison task or were not so instructed. Subjects instructed to use imagery could perform the task more quickly if they prepared themselves with an image of one of the objects at its normal size, rather than with an image that was abnormally big or small, or no image at all. Such subjects were also subject to substantial selective interference when asked to simultaneously maintain irrelevant images of digits. In contrast, when subjects were not specifically instructed to use imagery to reach their decisions, an initial image at normal size did not produce significantly faster decisions than no image, or a large or small image congruent with the correct decision. The selective interference created by simultaneously imaging digits was reduced for subjects not told to base their size comparisons on imagery. The difficulty of the size discrimination did not interact significantly with any other variable. The results suggest that subjects, unless specifically instructed to use imagery, can compare the size of objects in memory using information more abstract than visual imagery.     

Behavioral inference in young children

Three experiments are reported on behavioral inference in children of 3 to 5 years of age. In each experiment the children learned two separate sequences of behavior which they were required to put together in the final test stage in order to obtain a reward. In the first experiment moderate levels of behavioral inference were obtained, although a relatively high proportion of children failed to respond in the test phase. In the second experiment different instructions were used in the test phase, the number of nonresponders was greatly reduced and a much higher proportion of children showed behavioral inference. The third experiment obtained similar results under conditions which excluded the possibility of mediation during a memory test, which was included in the previous experiments. It was concluded that behavioral inference is found, under suitable conditions, in children as young as 3-years-old, and that reports by other investigators of failure to find such inference up to the age of about 8 were due to problems with apparatus and instructions.     

Development of binocular fixation in human infants

Two experiments measured changes in binocular eye alignment from 1- to 6-month-old human infants. In Experiment 1 changes in binocular eye alignment were recorded from 1, 2, and 3 month olds using corneal photography. A luminous target was moved along the infant's midline at one of two constant speeds. Infants at all three ages showed some evidence of appropriate changes in binocular eye alignment (convergence as the target approached and divergence as the target receded). The likelihood of appropriate convergence and divergence increased with age, as did the ability to respond appropriately to the faster target motion. A measure of convergence lag (further decrease in interpupillary distance after target motion had ended) was obtained for trials on which the target approached the infant. Convergence lag decreased with age and was greater on trials at the faster target speed until 3 months of age. Experiment 2 measured the responses of 3, $\text{4}\text{1}\text{2}$, and 6 month olds as a wedge prism was placed alternately in front of each eye. The prism displaced the image nasally (either 2.5° or 5°), creating inappropriate binocular eye alignment. A refixation eye movement in response to the prism was not present consistently until 6 months of age. Hypotheses as to the mechanism controlling infant binocular eye alignment are discussed with respect both to the present findings and to findings from human adults and animals.