Response-reinforcer contingency and spatially defined operants: testing an invariance property of phi

A chamber containing 72 response keys defining the circumference of a circle 1 m in diameter was used to examine the relation between differentiation of response location and a measure of response-reinforcer contingency known as the phi coefficient. A different target key was specified in each successive phase, and response location was differentiated with respect to the target. Criterional and noncriterional responses (i.e., responses "near" and "far" from the target) were defined using targeted percentile schedules to control the overall probability of each response class. By manipulating criterional (and, hence, noncriterional) response probability and the reinforcement probabilities conditional on each, a mathematical invariance property peculiar to phi in contingency analysis was examined. Specifically, diagonally interchanging cell frequencies in a 2 x 2 table relating criterional/noncriterional responses to reinforcement/nonreinforcement leaves phi unchanged. Hence, the degree of response differentiation predicted by phi remains unchanged under the four permutations implied by the various diagonal interchanges. This predicted invariance was examined under values of phi equal to .33, .58, and .82. Increasing phi generally increased the stereotypy of response location. Three of the permutations generated almost interchangeable performance at different phi values. The remaining permutation, however, generated functions relating response concentration to phi with slopes shallower than those obtained under the other permutations. This resulted from relatively higher levels of differentiation, compared to the other permutations, at low phi values. These data strongly suggest boundary conditions on the ability of phi to reflect completely the local processes that are indexed by phi at a molar level.     

Contiguity and contingency in the acquisition and maintenance of an operant

Three experiments compared the effects of nondifferential and differential reinforcement of response location on a circular dimension. Rats were required to operate a vertical joystick to produce food. When food was delivered immediately after responses, but independent of response location, the spatial concentration of responding was low and no progressive changes were observed. Traditional and percentile schedules of differential reinforcement for response location produced highly reliable acquisition of spatially concentrated responding. Once concentrated responding had been established, nondifferential reinforcement was sufficient to maintain it in some subjects. Since only the differential reinforcement schedules established a contingency with respect to response location, it was concluded that this relationship was necessary for acquisition, but that response-reinforcer contiguity may be sufficient for maintenance. This conclusion is consistent with the view that operant conditioning is a contiguity-based process, but that contingencies are required to produce reliable contiguity between reinforcers and particular responses.     

Synonym and antonym pairs in the detection of dichotically and monaurally presented targets: Competing monaural stimulation can generate a substantial right ear advantage

Aligned pairs of spoken words were presented, and the subject timed in detecting the presence or absence of a prespecified target. The target, if present, was paired with either its synonym or its antonym or an unrelated word. If the target was absent, mutually synonymous, antonymous or unrelated word pairs occured. In experiment 1, presentation of the word pairs was dichotic, and in experiment 2 the same stimuli were now systematically presented to a single ear (competing monaural stimulation). In both cases a strategy of divided attention was imposed with respect to the words. A powerful REA was obtained in the second experiment, demonstrating that this phenomenon does not depend upon occlusion of the ipsilateral by the contralateral auditory pathways (Kimura 1961), but that competition within ears is sufficient. Secondly, the nature of the effect (facilitatory or interfering) from a co-present synonym or antonym of the target depends markedly upon how the ears are stimulated, in partial contrast to and extending the results of Lewis (1970).     

Memory strategies in absolute identification of “circular” pitch

Shepard (1964) has devised a sequence of synthesized tones that appear to constitute a “circular” pitch dimension; each tone in the sequence appears to be higher in pitch than the preceding one, and yet the first tone also seems higher than the last. Two series of such stimuli (a six-alternative and an eight-alternative set) were used to investigate memory processes in absolute identification performance when end stimuli are unavailable as possible anchors. Clear evidence was obtained for short-term anchoring strategies in this task, but none was obtained for the stable retention of those stimuli corresponding to the ends of the response continuum. The results are examined in the light of Eriksen and Hake’s (1957) subjective-standard hypothesis.     

Interresponse-time shaping by variable-interval-like interresponse-time reinforcement contingencies

The interresponse-time reinforcement contingencies and distributions of interreinforcement intervals characteristic of certain variable-interval schedules were mimicked by reinforcing each key peck with a probability equal to the duration of the interresponse time it terminated, divided by the scheduled mean interreinforcement interval. The interresponse-time reinforcement contingency was then eliminated by basing the probability of reinforcement on the fifth interresponse time preceding the key peck. Even though distributions of interreinforcement intervals were unaffected by this manipulation, response rates consistently increased. A second experiment replicated this effect and showed it to combine additively with that of mean reinforcement rate. These results provide strong support for the contention that current analyses of variable-interval response rates that ignore the inherent interresponse-time reinforcement contingency may be seriously in error.