H. Keith Rodewald

Symbolic Matching-to-Sample by Pigeons

Pigeons were given 4 sessions, 90 reinforcers per session, in which the center one of three response keys was illuminated with red and green light. 40 responses on the center key produced side keys displaying white vertical and horizontal lines on black backgrounds. Red was “symbolically” matched by responding to the vertical lines and green by choice of the horizontal lines. A 25-sec. intertrial interval and a correction procedure for errors were in force. 90% or better matching occurred on the third session. A transfer task was derived by using figures as samples and colors as comparison stimuli. Reversal of the positions greatly disrupted performance. The animals learned to respond in the presence of each sample but did not appear to have learned the symbolic relations between colors and figures.

Effects of Serial Learning on Recognition Thresholds

Different groups of Ss were given various amounts of practice on a serial list of nonsense syllables. The usual bow-shaped curve of correct anticipations as a function of serial position was obtained. The syllables were then exposed in a tachistoscope and their recognition thresholds were determined by the method of constant stimuli. Analysis of variance of the probabilities of correct recognition as a function of frequency, serial position, and stimulus duration indicated stimulus duration was the only significant determiner of the probabilities. The usual threshold-frequency relationship was not observed.

Information transmission in brief exposures as a function of association value.

The amount of information Transmitted as a function of Glazes (1928) association value of nonsense syllables was determined by tachistoscopic presentation of the syllables for 30-msec. durations. S attempted to identify which syllabic of a known set of syllables had been exposed. The information theory meaure of transmission indicated a direct relation between association value and recognizability.

A conjoint-measurement analysis of control by dimensions of compound stimuli.

3 chickens were trained on a go/no-go discrimination in which S+ was three white dots in a vertical array on a red background and S– was three white dots in a horizontal array on a green background. The nine combinations of red, yellow and green backgrounds with vertical, 45° and horizontal arrays of dots were presented in extinction. A conjoint-measurement analysis was discussed, and the orientation and color dimensions were shown to be independent and additive.

Frequency-Threshold Relation With Association Value Controlled.

An experiment was performed in which the tachistoscopic recognition threshold for nonsense syllables was the dependent variable. Glaze association value (AV), print size (between-Ss effects), and frequency of prior exposure of the syllables (within-Ss effect) were the independent variables. Analysis of variance indicated significance (p = .05) for size and frequency main effects. Thresholds decreased with increasing size and frequency. The AV main effect and the interactions were not significant, although the trend suggested an inverse relation between AV and thresholds. The findings as an extension of earlier work and as evidence for a perceptual factor in the frequency-threshold relation were discussed.

Forgetting of Matching-to-Sample in Pigeons

A 10-wk. rest between acquisition and relearning sessions produced a clear decline in performance on a matching-to-sample task. The pigeons relearned matching quickly, and savings scores based on errors ranged from 0.43 to 0.62.

QUANTITATIVE ANALYSIS OF ACQUISITION OF A CONDITIONAL DISCRIMINATION

When the center one of three keys was illuminated with one of six stimuli, 40 pecks produced white light on both side keys. Three of the six stimuli set the conditions for reinforcement of a subsequent single peck on the left key, and three occasioned reinforcement for a right-key response. Three pigeons reached a criterion of 18 correct side-key responses in the last 20 presentations of each of the six stimuli. Prior to criterion, responding was stable and near chance levels; immediately thereafter, accuracy rose to 90% correct choices. Results of several statistical tests and good congruence with predictions of Bowers (1961) model suggested acquisition in an all-or-none manner and confirmed Rodewalds (1973) results.

Effects of Dimensionality, Pacing, and Sex on Oddity Problem Performance of Kindergarten Students

32 Ss were randomly selected from classes of kindergarten students in a small community elementary school. Ss filled a 2 × 2 × 2 randomized factorial design based on sex, time stress, and number of irrelevant dimensions. Dimensions were not irrelevant and one irrelevant; there were self-timed trials and 2-sec. response-limit trials. Proportion correct responses were recorded. Only time was significant: Ss in the self-timed condition performed significantly better than Ss in the 2-sec. hold-down condition.