Biomedical subjects

Kennon A Lattal

Publications and source records attributed to Kennon A Lattal.

12 recordsLinked to original sources

PubMed2006

Disruption of responding maintained by conditioned reinforcement: alterations in response-conditioned-reinforcer relations.

An observing procedure was used to investigate the effects of alterations in response-conditioned-reinforcer relations on observing. Pigeons responded to produce schedule-correlated stimuli paired with the availability of food or extinction. The contingency between observing responses and conditioned reinforcement was altered in three experiments. In Experiment 1, after a contingency was established in baseline between the observing response and conditioned reinforcement, it was removed and the schedule-correlated stimuli were presented independently of responding according to a variable-time schedule. The variable-time schedule was constructed such that the rate of stimulus presentations was yoked from baseline. The removal of the observing contingency reliably reduced rates of observing. In Experiment 2, resetting delays to conditioned reinforcement were imposed between observing responses and the schedule-correlated stimuli they produced. Delay values of 0, 0.5, 1, 5, and 10 s were examined. Rates of observing varied inversely as a function of delay value. In Experiment 3, signaled and unsignaled resetting delays between observing responses and schedule-correlated stimuli were compared. Baseline rates of observing were decreased less by signaled delays than by unsignaled delays. Disruptions in response-conditioned-reinforcer relations produce similar behavioral effects to those found with primary reinforcement.

Animals↗

PubMed2006

An analysis of reinforcement history effects.

Four pigeons were exposed to two tandem variable-interval differential-reinforcement-of-low-rate schedules under different stimulus conditions. The values of the tandem schedules were adjusted so that reinforcement rates in one stimulus condition were higher than those in the other, even though response rates in the two conditions were nearly identical. Following this, a fixed-interval schedule of either shorter or longer values than, or equal to the baseline schedule, was introduced in the two stimulus conditions respectively. Response rates during those fixed-interval schedules typically were higher in the presence of the stimuli previously correlated with the lower reinforcement rates than were those in the presence of the stimuli previously correlated with the higher reinforcement rates. Such effects of the reinforcement history were most prominent when the value of the fixed-interval schedule was shorter. The results are consistent with both incentive contrast and response strength conceptualizations of related effects. They also suggest methods for disentangling the effects of reinforcement rate on subsequent responding, from the response rate with which it is confounded in many conventional schedules of reinforcement.

Animals↗

PubMed2005

Contextual determinants of temporal control: Behavioral contrast in a free-operant psychophysical procedure.

The question of how temporal control of responding might be influenced by contingency changes in other contexts was investigated. Each of three pigeons first was exposed to a two-component multiple schedule in which a two-key free-operant psychophysical procedure operated in one component and a variable-interval schedule operated in the other component. The variable-interval schedule then was changed to extinction while the free-operant psychophysical procedure remained unchanged. Finally, the variable-interval schedule was reintroduced. Response rates on the left key and the estimated temporal threshold under the free-operant psychophysical procedure increased for each pigeon when the alternate component schedule was changed to extinction and then decreased again when the variable-interval schedule was reintroduced. The results suggest one way that temporal control is affected by its context, and may be interpreted through the direct effects of overall reinforcement rate on temporal control mechanisms or the disruptive effects of alternative sources of reinforcement on temporally controlled behavior.

Animals↗

PubMed2005

Variation, repetition, and choice.

Experiment 1 investigated the controlling properties of variability contingencies on choice between repeated and variable responding. Pigeons were exposed to concurrent-chains schedules with two alternatives. In the REPEAT alternative, reinforcers in the terminal link depended on a single sequence of four responses. In the VARY alternative, a response sequence in the terminal link was reinforced only if it differed from the n previous sequences (lag criterion). The REPEAT contingency generated low, constant levels of sequence variation whereas the VARY contingency produced levels of sequence variation that increased with the lag criterion. Preference for the REPEAT alternative tended to increase directly with the degree of variation required for reinforcement. Experiment 2 examined the potential confounding effects in Experiment 1 of immediacy of reinforcement by yoking the interreinforcer intervals in the REPEAT alternative to those in the VARY alternative. Again, preference for REPEAT was a function of the lag criterion. Choice between varying and repeating behavior is discussed with respect to obtained behavioral variability, probability of reinforcement, delay of reinforcement, and switching within a sequence.

Animals↗

PubMed2005

Unsignaled delay of reinforcement, relative time, and resistance to change.

Two experiments with pigeons examined the effects of unsignaled, nonresetting delays of reinforcement on responding maintained by different reinforcement rates. In Experiment 1, 3-s unsignaled delays were introduced into each component of a multiple variable-interval (VI) 15-s VI 90-s VI 540-s schedule. When considered as a proportion of the preceding immediate reinforcement baseline, responding was decreased similarly for the three multiple-schedule components in both the first six and last six sessions of exposure to the delay. In addition, the relation between response rates and reinforcement rates was altered such that both parameters of the single-response version of the matching law (i.e., k and Re) were decreased. Experiment 2 examined the effects of unsignaled delays ranging from 0.5 s to 8.0 s on responding maintained by a multiple VI 20-s VI 120-s schedule of reinforcement. Response rates in both components increased with brief unsignaled delays and decreased with longer delays. As in Experiment 1, response rates as a proportion of baseline were affected similarly for the two components in both the first six and last six sessions of exposure to the delay. Unlike delays imposed between two stimulus events, the effects of delays between responses and reinforcers do not appear to be attenuated when the average time between reinforcers is longer. In addition, the disruptions produced by unsignaled delays appear to be inconsistent with the general finding that responding maintained by higher rates of reinforcement is less resistant to change.

Animals↗

PubMed2004

Psychological distance to reward: equating the number of stimulus and response segments.

Psychological distance to reward, or the segmentation effect, refers to the preference for a terminal link of a concurrent-chains schedule consisting of a simple reinforcement schedule (e.g. fixed interval [FI] 30s) relative to its chained-schedule counterpart (e.g. chained FI 15s FI 15s). This experiment was conducted to examine whether the segmentation effect is due to the number of terminal-link stimulus and response segments per se. Three pigeons pecked under a concurrent-chains schedule in which identical variable-interval (VI) schedules operated in the initial links. In each session, half the terminal-link entries followed one initial-link key and the other half followed the other initial-link key. The initial-link keys correlated with the different terminal links were manipulated across conditions. In the first three conditions, each terminal link contained a chained fixed-time (FT) FT schedule, and in the final three conditions, each terminal link contained a chained FI FI schedule. In each condition, in one terminal link (alternating), the order of two key colors correlated with the different schedule segments alternated across terminal-link entries, whereas in the other terminal link (constant), the order of two other key colors was identical for each entry. With the chained FT FT schedule terminal links, there was indifference between the alternating and constant terminal links within and across pigeons, as indexed by initial-link choice proportions. In addition, terminal-link response rates were relatively low. With the chained FI FI schedule terminal links, for each pigeon, there was relatively more preference for the alternating terminal link and terminal-link response rates increased relative to conditions with the chained FT FT schedule terminal links. These data suggest that the segmentation effect is not due simply to the number of terminal-link stimulus or response segments per se, but rather to a required period of responding during a stimulus segment that never is paired with reinforcement.

Adaptation, Psychological↗

PubMed2004

Within-session delay-of-reinforcement gradients.

Within-session delay-of-reinforcement gradients were generated with pigeons by progressively increasing delays to reinforcement within each session. In Experiment 1, the effects of imposing progressive delays on variable-interval and fixed-interval schedules were investigated while controlling for simultaneous decreases in reinforcer rate across the session via a within-subject yoked-control procedure. Rate of key pecking decreased as a negatively decelerated function of delay of reinforcement within a session. These rate decreases were greater than those during a yoked-interval session in which the rate of immediate reinforcement decreased at the same rate as it did under the progressive-delay procedure. In Experiment 2, delay-of-reinforcement gradients were shallower when the progressive delay intervals were signaled by a blackout than when they were unsignaled. The delay gradients obtained in each experiment were similar to those generated under conditions in which different delays of reinforcement are imposed across blocks of sessions. The present procedure offers a technique for rapidly generating delay-of-reinforcement gradients that might serve as baselines for assessing the effects of other behavioral and pharmacological variables.

Animals↗

PubMed2004

Steps and pips in the history of the cumulative recorder.

From its inception in the 1930s until very recent times, the cumulative recorder was the most widely used measurement instrument in the experimental analysis of behavior. It was an essential instrument in the discovery and analysis of schedules of reinforcement, providing the first real-time analysis of operant response rates and patterns. This review traces the evolution of the cumulative recorder from Skinner's early modified kymographs through various models developed by Skinner and his colleagues to its perfection in the 1950s, and then into the 1960s when it proliferated as different scientific instrument companies began marketing their own models of the cumulative recorder. With the rise of digital computers, the demise of the cumulative recorder as a scientific instrument was inevitable; however, the value of the cumulative record as a monitoring device to assess schedule control of behavior continues. The cumulative recorder remains, along with the operant conditioning chamber, an icon of Skinner's approach to psychology.

Behaviorism↗

PubMed2004

Differential reinstatement predicted by preextinction response rate.

Reinstatement refers to the recovery of previously extinguished responding by the response-independent delivery of a stimulus that was a reinforcer in training. Two experiments were conducted to examine relative reinstatement following the training of differential preextinction response rates, either with equal (Experiment 1) or unequal (Experiment 2) preextinction reinforcement rates. In Experiment 1, each of 3 pigeons first pecked at relatively high rates in the tandem variable-time 117-sec fixed-interval 3-sec component of a multiple schedule and at lower rates in a separate tandem variable-interval 117-sec fixed-time 3-sec component. Reinforcement rates were equal between components. Pecking then was extinguished in each component, before being reinstated under a multiple variable-time 120-sec variable-time 120-sec schedule. Greater reinstatement occurred in the component previously correlated with higher rates of pecking. In Experiment 2, in an initial condition, the mean rate of lever pressing for one group of 8 rats was significantly higher under a fixed-ratio 3 schedule than for another group of 8 rats under a fixed-ratio 1 schedule. Mean reinforcement rate was significantly higher for the group exposed to the fixed-ratio 1 schedule. For each group, lever pressing then was extinguished, before being reinstated under a variable-time 30-sec schedule. Significantly greater mean reinstatement occurred for the group previously exposed to the fixed-ratio 3 schedule. These results suggest that differential reinstatement may be predicted by preextinction response rate, perhaps independently of preextinction reinforcement rate.

Animals↗

PubMed2003

Using visual reinforcement to establish stimulus control of responding of Siamese fighting fish (Betta splendens).

Stimulus control of ring swimming was studied with male Siamese fighting fish (Betta splendens) using 2-component multiple schedules in which the components were correlated with the presence or absence of air bubbles in the water. In Experiment 1, either response-independent mirror presentations or extinction was juxtaposed with immediate response-dependent mirror presentations. Rates of ring swimming generally were higher with immediate reinforcement than with either response-independent mirror presentations or extinction. In Experiment 2, different durations of response-dependent mirror presentations were juxtaposed. Generally, higher rates of ring swimming occurred with 15-s than with 0-, 1-, or 3-s durations. Results demonstrate that stimulus control of responding can be established with these fish under several conditions of differential reinforcement.

Animals↗

PubMed2003

Response persistence under variable-time schedules following immediate and unsignalled delayed reinforcement.

Key pecking of three pigeons was maintained in separate components of a multiple schedule by either immediate reinforcement (i.e., tandem variable-time fixed-interval schedule) or unsignalled delayed reinforcement (i.e., tandem variable-interval fixed-time schedule). The relative rate of food delivery was equal across components, and this absolute rate differed across conditions. Immediate reinforcement always generated higher response rates than did unsignalled delayed reinforcement. Then, variable-time schedules of food delivery replaced the contingencies just described such that food was delivered at the same rate but independently of responding. In most cases, response rates decreased to near-zero levels. In addition, response persistence was not systematically different between multiple-schedule components across pigeons. The implications of the results for the concepts of response strength and the response-reinforcer relation are noted.

Animals↗

PubMed2003

Recency, repeatability, and reinforcer retrenchment: an experimental analysis of resurgence.

Four experiments were conducted with pigeons to assess the experimental conditions necessary for the occurrence of resurgence. The general procedure consisted of the following conditions: Condition 1--reinforcement of key pecking; Condition 2--reinforcement of treadle pressing and concurrent extinction of key pecking; and Condition 3--the resurgence condition wherein resurgence was defined as the recovery of key pecking. In Experiments 1 and 2, the resurgence condition was conventional extinction. The effect of recency on resurgence magnitude was examined in Experiment 1 by manipulating the number of sessions of Condition 2, above. Resurgence was not a function of recency with the parameters used. Repeating the three conditions revealed resurgence to be a repeatable effect in Experiment 2. In Experiment 3, a variable-time schedule was in effect for the resurgence condition. Resurgence was not produced by response-independent food delivery. In Experiment 4, the resurgence condition was a variable-interval schedule for treadle pressing that arranged a lower reinforcement rate than in Condition 2 (92% reduction in reinforcers per minute). Resurgence was lower in magnitude relative to conventional extinction, although resurgence was obtained with 2 out of 3 pigeons. The results are discussed in terms of the variables controlling resurgence and the relations between behavioral history, resurgence, and other forms of response recovery.

Animals↗