The internal representation of numbers

A principle of second-order isomorphism asserts that the functional similarities among internal representations parallel the structural similarities among the external objects to which those representations correspond. In accordance with this principle, subjects were asked to rate the similarities of all pairs of the numbers 0 through 9 in each of 24 conditions distinguished by the forms into which they were to be mentally transformed and then judged-including the visual forms of rows of dots and Arabic numerals, the auditory form of spoken English names, and the amodal form of the abstract concepts of the integers themselves. Similarity ratings were found to depend entirely upon the form in which the numbers were to be judged and not at all upon the form in which they were actually presented. Regardless of the form presented, multidimensional scaling solutions for each of the 24 conditions were readily interpretable in terms of structural properties of the form judged-curvature and closure for visual numerals; number of syllables, initial consonant, and vowel phoneme for auditory names; and numerical magnitude, odd-evenness, etc., for abstract concepts. Reanalyses of chronometric data are presented to illustrate how a fuller understanding of human cognitive processes may be attainable by using such structural models of internal representation in conjunction with studies of overt confusion and reaction time.     

APE: average potential evaluation software for the LAB-8 system

A paper-tape software system is described which allows the addition and/or subtraction of signal averaging data from the DEC advanced averager program. This pooled averaging data may be plotted, printed, or punched. A DEC LAB-8 system with 4K memory and high-speed reader/punch are required. Several examples of the application of the system to human evoked brain response data are presented, and the application of the system to other problems is discussed.     

The time required to prepare for a rotated stimulus

Average time required to determine whether an alphanumeric character was presented in its normal version or as its mirror image increased from 500 msec to 1,000 msec as its angular departure from upright increased from 0 to 180 deg. However, when Ss already knew the identity of the upcoming character and when advance information as to its orientation was available for 1,000 msec, this reaction time was reduced to about 400 msec regardless of the orientation of the test stimulus. In this case, Ss claimed that they could prepare for the rotated stimulus by imagining the normal version of the designated character rotated into the indicated orientation and that they could then rapidly test for a match against the ensuing stimulus.     

Perceptual-cognitive explorations of a toroidal set of free-form stimuli

A polar-coordinate analogue of Fourier synthesis generates organic-appearing “free forms” that can be continuously deformed along any desired number of difficult-to-verbalize dimensions. Since the dimensions are also circular, the forms correspond to points on the surface of a torus which, though conveniently finite, is free of bounding edges. Two experiments explore a particular two-dimensional set of 81 such forms. The first shows that perceived pair-wise similarities among the individual forms are well explained purely in terms of the distances among their corresponding points in the toroidal parameter space. The second, however, establishes that forms that tend to be grouped together as having the same cognitive interpretation define regions in parameter space that are variously shaped or even bimodal and, hence, that cannot be explained solely on the basis of the fixed set of pair-wise similarities. The stimuli appear to offer a novel combination of cognitive richness and low-dimensional parametric control.     

A simple tachistoscope for student labs

An inexpensive tachistoscope for student labs is described that utilizes a camera shutter to control exposure duration and a potentiometer to vary light intensity. Stimuli can be drawn or typed on 3 x 5 index cards.     

Perceived rotary motion from changes in a straight line

The problem dealth with was how perception of a three-dimensional space is related to the corresponding two-dimensional retinal image. The stimulation used was a straight line changing length and direction. For this stimulation a geometrical model was developed. The basic decoding principle in this model is that the changes in the two-dimensional figure will be perceived as three-dimensional motions of an object with constant shape and size. This principle was approximately verified for the majority of the data. The main deviation from the model was that there was generally less perceived depth than predicted. Also a second decoding principle was generally verified: rotary, but not translator motion is perceived from this kind of stimulation. A third unexpected decoding principle was found in the data: the line is perceived in a frontal-parallel direction when it has its maximal extention.     

Changes in Accuracy of Self-Estimates

Subjects in this study were 100 ninth-grade students who expressed an interest in receiving test results. Subjects were assigned to one of four groups on the basis of self-regard measures. Treatment consisted of reporting standardized test results to the experimental groups but not to the control groups. Immediately following test reporting and two weeks afterward, students characterized by high self-regard made significantly more accurate self-estimates of interests, aptitudes, and achievements than did low self-regard students. In addition, accuracy of self-estimates was significantly greater for students receiving reports of test results than for students not receiving test results.     

A comparison between “aware” and “naive” conditions in the suppression of GSR activity

“Aware” (A) and “naive” (N) groups received different instructional sets, the former being informed both of the nature of their task and the response-reinforcement contingency. Negative reinforcement was given to these groups whenever a spontaneous GSR was emitted during four 4-min trial periods. Two corresponding yoked-control groups, CA and CN, received non-contingent reinforcement over the same periods. The contingent reinforcement groups both showed learned suppression of spontaneous GSR activity, but comparison between the A and N groups revealed a significant interaction between Time and Instructional Set. It is suggested that the “aware” instructional set had an inhibitory effect upon learning.