Cognitive factors affecting sequential dependencies in differential eyelid conditioning

Sequential dependencies were examined as a function of learning, masking, and subject factors in a two-stage differential eyelid conditioning experiment. In Stage 1, all subjects were differentially conditioned to two Vanderplas and Garvin (1959) forms. In Stage 2, the conditional stimuli (CSs) were one of eight words, four reinforced (CS+) and four unreinforced (CS?), with taxonomic category (animalsvs. musical instruments) as the discriminandum, and different subjects were given semantic, physical, or no additional CS processing tasks. The results showed sizeable and highly significant sequential dependencies in the form of greater conditional response probabilities when CS + as opposed to CS? trials were recently experienced. These effects decreased overtrials, were greater in the groups given additional processing loads, and were in some cases greater in C-form responders than in V-form responders and greater in subjects who were unable to verbalize the differential contingencies. It was concluded that the magnitude of sequential dependencies was inversely related to the subject’s awareness of the differential contingencies and/or ability to use the contingency information to respond appropriately to the CS cues.     

Fading and errorless transfer in successive discriminations

A successive discrimination between red positive and green negative stimuli was established with pigeon subjects. Then, lines with different angular orientations were superimposed on one of the colors to form compound stimuli. Finally, either the colored element of the positive compound, the colored element of the negative compound, or both colored elements together, were gradually attenuated. Before each attenuation, the line elements were presented alone against dark backgrounds as probes to assess the degree to which they had acquired control of responding. When the positive color was attenuated alone or in conjunction with the negative color, angular orientation acquired control of responding in an errorless fashion. Lines, however, did not acquire control when only the negative component was attenuated. These results were interpreted in terms of changes in the predictability of reinforcement by color and line elements during stimulus attenuation. Finally, attenuation of the negative stimulus influenced the number of “dimensions” of the new line stimuli that acquired control of responding. When the positive stimulus was attenuated with the negative, only one dimension of the lines acquired control. When the positive stimulus was attenuated without the negative, however, more than one dimension of the lines acquired control of responding. These results were interpreted in terms of how errorless performance can be maintained while an organism attends to different dimensions of the new stimuli.     

Delayed and current stimulus control in successive discriminations

In a successive discrimination in which successively alternating red and green hues signaled component variable-interval schedules, sensitivity of the ratio of responses in the two components to variation in the component reinforcer ratio decreased systematically during the course of the component. This decrease in stimulus control or discrimination over the course of the component was shown to be the result of delayed control of responding during the component by the stimulus transition between components. When the red–green stimulus transition was altered by interpolating a white stimulus at the end of each 60-s component, discrimination at the beginning of the component (measured by the power-function exponent for sensitivity to reinforcement) was reduced. Conditions with the white stimulus inserted in other quarters of the component indicated that the current discriminative stimulus exerts control over responding throughout the component, whereas during about the first half of the component, response differentials are influenced by the transition between discriminative stimuli.     

Cognitive factors in the concurrent differential conditioning of eyelid and skin conductance responses

The objectives of the study were to (1) determine if differential conditioning of eyelid responses ocurs only among subjects who accurately report knowledge of the CS-UCS relations, (2) assess whether differentially conditioned eyelid responding occurs only after the initial accurate interrial report, and (3) explore characteristics of differentially conditioned skin conductance responses (SCRs) obtained in an eyelid conditioning paradigm, with special attention to whether eyelid and SCR conditioning are similarly related to the subjects’ knowledge of the stimulus relations. Fifty-one male subjects were administered 80 differential eyelid conditioning trials, the CSs consisting of the 1,200-msec illumination of slides containing either grammatically correct or grammatically incorrect phrases. Significant differential SCR and eyelid conditioning was obtained for both V- and C-form eyelid responders, but only for subjects who accurately reported the CS-UCS relations. The initial appearance of SCR and eyelid differentiation was related within the trial sequence to subjects’ recognition of the stimulus relations. Eyelid and SCR conditioning were related similarly to knowledge of the stimulus relations, the exception being that subjects who recognized the stimulus relations late in the trial sequence did not develop reliable eyelid differentiation.     

Transfer of control in ambiguous discriminations

Rats' acquisition and transfer of performance in ambiguous discriminations was examined using discrete-trial operant lever-press procedures. Rats learned serial ambiguous discriminations (X----A+, A-; B+, X----B-) by acquiring both positive and negative occasion setting functions to the X feature. Mutual transfer occurred among cues from serial ambiguous, feature positive (Y----C+, C-), and feature negative (Y----C-, C+) discriminations, but that transfer did not extend to cues not trained within one of those serial discriminations. The ambiguous feature's positive occasion setting powers were unaffected by nonreinforced presentation of that feature alone, and posttraining counterconditioning did not eliminate the feature's ability to serve as a negative occasion setter. Occasion setting was not acquired with simultaneous ambiguous discriminations (XA+, A-; XB-, B+), which apparently were solved with a configural strategy.     

Concurrent assessment of schedule and intensity control across successive discriminations

Two chinchillas were trained on a series of two-valued auditory intensity discriminations. Lever presses were reinforced when no tone was present and not reinforced in the presence of a four-kiloHertz tone. The intensity of the nonreinforced tone was successively decreased, increasing the difficulty of the discrimination, until differential responding resembled that on a mixed schedule (no-tone–no-tone). Response data were partitioned in such a way as to provide a continuing assessment of the relative amounts of control exerted by the reinforcement schedule and the sound intensity, respectively. Control by reinforcement density was a direct function of discrimination difficulty, whereas the control exerted by intensity was inversely related to difficulty. For these chinchillas, the absolute threshold value obtained at four kiloHertz was about two decibels referenced to 20 microNewtons per meter squared.