International Journal of Psychology and Psychological Therapy

Volume 4 Num. 1 - April 2004


Human Observing Behavior Maintained by S+ and S-: Preliminary Data [Comportamiento de Observaci?n en Humanos Mantenido por S+ y S-: Datos Preliminares]

Volume 4 Num. 1 - April 2004 - Pages 155-163


Gerson Yukio Tomanari


The present study approaches the assessment of the reinforcing function of stimuli that signal the presence (S+) versus the absence (S-) of reinforcement. Two college students participated. A computer application presented a random sequence of two different types of discrete 18-s trials separated by 4-s intertrial intervals. Half of the trials ended with reinforcement (points delivery), and half with no reinforcement. All trials started with a mixed-schedule stimulus being displayed on the center of the monitor screen. Space-bar presses (observing responses) in its presence could change it for either one of two other stimuli correlated with the current type of trial. The schedule requirements for observing responses varied across phases. During baseline, the production of both S+ and S- was under similar schedules of reinforcement (continuous reinforcement or variable interval schedules). During experimental phases, in addition to the baseline schedules, a minimum interresponse time (IRT) was required in order to either S+ (in one experimental condition) or S- (in the other one) be presented. The evaluation of the reinforcing function of S+ relative to S- was assessed by a cross-condition comparison, particularly by the participants? observing responding when the IRT requirement was operative. Results showed that when the presentation of S+ and S- was under these conditions, both stimuli were produced, although often in lower frequencies than in baseline, as one would expect when considering the higher demand added by the IRT. However, for both participants, S+ was produced 20% more often than Swhen comparable conditions were in effect. This higher production of S+ may be suggesting a higher effectiveness of S+ as a conditioned reinforcer, although the reinforcing function of Sseems also to exert a major role in the maintenance of human observing responses.

Key words:

observing responses, conditioned reinforcement, human participants.

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