Biomedical subjects

W L Palya

Publications and source records attributed to W L Palya.

4 recordsLinked to original sources

PubMed1993

Bipolar control in fixed interfood intervals.

The ability of stimuli correlated with successive periods in a fixed interfood interval to support a response that produced or removed them was examined using pigeons. The degree to which those correlated stimuli elicited directed key pecks was also obtained. Stimuli early in the interval functioned as negative reinforcers, and stimuli late in the interval functioned as positive reinforcers. Stimuli correlated with successively later portions of the second half of the interval supported successively higher rates of elicited pecking and, with the exception of the final stimulus, supported successively higher rates of stimulus production. Stimuli in successively earlier portions of the first half of the interval supported successively higher rates of correlated-stimulus removal. This effect occurred in spite of the addition of a conjoint variable-interval dependency for food. An ogive fit to the mean normalized response distributions resulted in r(2)s demonstrating that most of the variance in the temporal organization of the behavior was accounted for. The findings were taken to indicate that fixed interfood intervals establish bipolar control.

Journal Article↗

PubMed1992

Dynamics in the fine structure of schedule-controlled behavior.

The variability in the behavioral equilibrium established by six basic schedules was characterized. The measures were the pause preceding the first response in each interreinforcement interval; the mean rate of responding in each interreinforcement interval; and the relative frequency of each interresponse time. The temporal windows ranged across the 780-session exposure, across a session, and across the interreinforcement interval. A display of individual interresponse times as a function of time in the interreinforcement interval indicated clear recurrent responding at somewhat less than 3 Hz in every bird, even after extended exposure to a schedule and regardless of the contingency. No strong sequential dependencies in the interresponse-time distributions were identified. A simulator, based on a simple recurrent pulser, was presented that produced output similar to the obtained data. An archival data base of the behavior chronically maintained by the simple schedules was also generated.

Animals↗

PubMed1990

Serial conditioning as a function of stimulus, response, and temporal dependencies.

Six experiments were used to examine the effects of explicit response, stimulus, and temporal dependencies on responding in an interfood interval. The first two experiments demonstrated that 10-segment 60-s interfood clocks controlled similar distributions of key pecking in pigeons regardless of whether response-reinforcement contiguity was required, allowed, or precluded. The third and fourth experiments found that in the absence of an explicit response-reinforcement dependency, systematic explicit stimuli in an interfood interval were sufficient to establish and maintain the characteristic distribution of key pecking and that an interval without an explicit clock failed to establish or maintain key pecking. The last two experiments demonstrated that the interfood interval need not be of fixed length, and that a simple correlation of stimuli with increments from either a minimum to a maximum imminency or probability of food presentation controlled behavior in a similar manner. Successively higher rates generally occurred to successively later stimuli in the upper half of the range.

Journal Article↗

PubMed1985

Sign-tracking with an interfood clock.

Food was presented to pigeons, irrespective of their behavior. The fixed 60-s interfood interval was segmented into ten 6-s periods, each signaled by a distinctive stimulus color, ordered by wavelength. This "interfood clock" reliably generated and maintained successively higher rates of key pecking at stimuli successively closer to food. Under extinction, key pecking ceased. When the standard stimulus sequence was changed to a different sequence for each bird, accelerated responding again emerged and was sustained under each of the new color sequences. However, responding was neither maintained nor acquired when each successive interfood interval provided a different random sequence of the ten stimuli. Thus, the interfood clock generated and maintained sign-tracking under stimulus control, and the resulting behavior was attributable neither to stimulus generalization nor to a simple temporal gradient.

Journal Article↗