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J Gibbon

Publications and source records attributed to J Gibbon.

17 recordsLinked to original sources
PubMed1992

Comparison of variance and covariance patterns in parallel and serial theories of timing.

Parallel and serial timing processes are analyzed for their account of the dynamics of intertrial responding in the peak procedure. A strictly serial model, such as the behavioral theory of timing (Killeen & Fetterman, 1988), does not fit the dynamic correlation pattern in the location and duration of the middle high-rate responding portion of peak trials. In contrast, the parallel scalar expectancy theory model, with a sample for memory and threshold, does fit this pattern. A modification of the serial model is presented that also accommodates the within-trial covariance pattern. The modification, which is formally equivalent to a model for human tapping (Wing & Kristofferson, 1973), entails the addition of concurrent processes operating in parallel with serial timing.

Animals↗
PubMed1990

Representation of time.

Memory representation for time was studied in two settings. First, an analysis of timing in a laboratory analog of a foraging situation revealed that departure times from a patchy resource followed a Weber Law-like property implied by scalar timing. A trial-by-trial analysis was then pursued in a similar but more structured experimental paradigm, the Peak procedure. Study of covariance structures in the data implicated scalar variance in the memory for time as well as in the decision process, but the correlation pattern ruled out multiple access to memory within a trial.

Animals↗
PubMed1990

Duration of signals for intertrial reinforcement and nonreinforcement in random control procedures.

In the random control procedure, responding to a conditioned stimulus (target CS) is prevented when the probability of unsignaled, unconditioned stimuli (USs) in the intertrial interval (ITI) is equal to the probability of the US in the presence of the target CS. Three experiments used an autoshaping procedure with White Carneaux pigeons to examine the effects of the temporal duration of signals for the ITI USs (cover CSs) and for concomitant periods of nonreinforcement. In Experiment 1, a short duration cover, but not a long duration cover, resulted in responding to the target CS. In Experiment 2, an explicit CS- cue during periods of nonreinforcement did not affect target acquisition. In Experiment 3, a long CS-, but not a short cover CS, was a sufficient condition for the acquisition of responding to the target CS. These results imply that the acquisition of responding to a target CS requires a discriminable period of nonreinforcement that is long relative to the target CS duration.

Animals↗
PubMed1988

Formation of tone-US associations does not interfere with the formation of context-US associations in pigeons.

In four experiments we investigated whether signaled and unsignaled US presentations resulted in differential context conditioning. Experiments 1 and 2 showed that the presence of a tone during grain presentation facilitated the formation of tone-food associations in pigeons. Experiment 2 also showed that the acquisition of associative value by the tone did not diminish associations between context and the unconditioned stimulus (US). Experiment 3 showed that signaled USs did not interfere with the acquisition of context-US associations, and Experiment 4 showed that even when the signal was extensively pretrained, context-US associations could not be blocked. The results of these experiments are inconsistent with conditioning models that require competition between cues and contexts for associative value.

Animals↗
PubMed1985

Temporal integration in duration and number discrimination.

Temporal integration in duration and number discrimination by rats was investigated with the use of a psychophysical choice procedure. A response on one lever ("short" response) following a 1-s white-noise signal was followed by food reinforcement, and a response on the other lever ("long" response) following a 2-s white-noise signal was also followed by food reinforcement. Either response following a signal of one of five intermediate durations was unreinforced. This led to a psychophysical function in which the probability of a long response was related to signal duration in an ogival manner. On 2 test days, a white-noise signal with 5, 6, 7, 8, or 10 segments of either 0.5-s on and 0.5-s off or 1-s on and 1-s off was presented, and a choice response following these signals was unreinforced. The probability of a long response was the same function of a segmented signal and a continuous signal if each segment was considered equivalent to 200 ms. A quantitative fit of a scalar estimation theory suggested that the latencies to initiate temporal integration and to terminate the process are both about 200 ms, and that the same internal accumulation process can be used for counting and timing.

Animals↗
PubMed1984

Daily meal anticipation: interaction of circadian and interval timing.

Both short-interval and circadian timing systems support anticipatory response accelerations prior to food reinforcement. In the first case, the behavior pattern is determined by a scalar timing process with an arbitrary-reset property. In contrast, under daily cycles of food-availability, behavior reflects a self-sustaining oscillation. With rats as subjects, the concurrent operation of timing of both kinds was studied by addition of premeal auditory cues on the circadian baseline, in the absence of a day-night illumination cycle. Cues within both minute and hour ranges served to lower the level of premeal anticipatory responding, although exponential accelerations were similar to the uncued case. Cues within the minutes range yielded interval-timing functions that reflected approximate superposition. Cues within the hours range suppressed respondings at their outset, in proportion to cue duration. When one of the shorter cues was suddenly lengthened, short-interval accelerations appeared at inappropriate circadian phases. When a premeal cue was extended through mealtime, anticipation rates increased markedly, suggesting that cue termination at the start of mealtime is a potent anchor for premeal anticipation regardless of cue duration. By use of meal-omission probes without external cues, peak rates were located after the onset of expected mealtime, often near its termination. The results suggest interactions between the scalar interval timer and the circadian anticipation timer, as modulated by the circadian free-run timer.

Animals↗
PubMed1984

Two kinds of timing in circadian incubation rhythm of ring doves.

Ring dove males share incubation with females by sitting on the nest for a block of time in the middle of the day. The timing of nest exchanges was studied by experimentally delaying the onset, in the morning, of the male's sitting bout. Such delays induced a concomitant but smaller delay in the offset of the male's sitting bout in the afternoon. The female, however, approached the nest to start her bout of sitting at the usual time in the afternoon even though her previous sitting bout had ended later than usual. These findings, together with data on interactions between the pair at the afternoon exchange, suggest that the behavior of the sitting male reflects an interval timing mechanism initiated with the onset of his sitting bout. In contrast the attempts to regain the nest by the nonsitting female probably reflect a circadian oscillation.

Animals↗
PubMed1983

Timing the second response in two-response avoidance.

Rats were trained on a free-operant avoidance task requiring two lever presses within R seconds, with the opportunity for each response distinguished by differing stimuli. Response latencies at a variety of response-shock intervals were found to be proportional to the time available for the response. These results are shown to be consonant with a scalar expectancy model of timing behavior.

Animals↗
PubMed1982

Temporal generalization.

Responses of 26 rats were reinforced following a signal of a certain duration, but not following signals of shorter or longer durations. This led to a positive temporal generalization gradient with a maximum at the reinforced duration in six experiments. Spacing of the nonreinforced signals did not influence the gradient, but the location of the maximum and breadth of the gradient increased with the duration of the reinforced signal. Reduction of reinforcement, either by partial reinforcement or reduction in the probability of a positive signal, led to a decrease in the height of the generalization gradient. There were large, reliable individual differences in the height and breadth of the generalization gradient. When the conditions of reinforcement were reversed (responses reinforced following all signals longer or shorter than a single nonreinforced duration), eight additional rats had a negative generalization gradient with a minimum at a signal duration shorter than the single nonreinforced duration. A scalar timing theory is described that provided a quantitative fit of the data. This theory involved a clock that times in linear units with an accurate mean and a negligible variance, a distribution of memory times that is normally distributed with an accurate mean and a scalar standard deviation, and a rule to respond if the clock is "close enough" to a sample of the memory time distribution. This decision is based on a ratio of the discrepancy between the clock time and the remembered time, to the remembered time. When this ratio is below a (variable) threshold, subjects respond. When three timing parameters--coefficient of variation of the memory time, the mean and the standard deviation of the threshold--were set at their median values, a theory with two free parameters accounted for 96% of the variance. The two parameters reflect the probability of attention to time and the probability of a response given inattention. These parameters were not influenced by stimulus manipulations but were affected by manipulations of reinforcement rate and by individual differences.

Animals↗
PubMed1981

Time left: linear versus logarithmic subjective time.

In two experiments, subjects were given a choice between a standard fixed interval to reinforcement and the time left to reinforcement in an elapsing comparison interval. In Experiment 1, rats were trained to respond on a comparison 60-sec fixed-interval schedule on one lever and a standard 30-sec fixed-interval schedule on a second lever. Then combined trials were given that began with the entry of the comparison 60-sec lever, followed by the standard 30-sec lever after 15, 30, or 45 sec. Rats preferred to respond on the standard lever when it entered early (at 15 sec), they preferred to respond on the comparison lever when the standard entered late (at 45 sec), and they were approximately indifferent between the two levers when the standard entered halfway through the comparison interval so that the remaining time to food was equal on both levers. In Experiment 2, pigeons were trained to choose between the time left to food in an elapsing comparison interval (C sec long) and a standard fixed interval one half as long (S = C/2) in a concurrent-chains paradigm. Birds came to choose the standard early and the comparison late in the trial interval. The indifference point was linearly related to the midpoint of the elapsing C interval at a variety of S,C pairs. The results of both experiments are consistent with a Scalar Timing theory in which subjective time is linear in real time and memory variance is scalar, and they are inconsistent with a logarithmic time scale.

Animals↗
PubMed1974

Contingency spaces and measures in classical and instrumental conditioning.

The contingency between conditional and unconditional stimuli in classical conditioning paradigms, and between responses and consequences in instrumental conditioning paradigms, is analyzed. The results are represented in two- and three-dimensional spaces in which points correspond to procedures, or procedures and outcomes. Traditional statistical and psychological measures of association are applied to data in classical conditioning. Root mean square contingency, Ø, is proposed as a measure of contingency characterizing classical conditioning effects at asymptote. In instrumental training procedures, traditional measures of association are inappropriate, since one degree of freedom-response probability-is yielded to the subject. Further analysis of instrumental contingencies yields a surprising result. The well established "Matching Law" in free-operant concurrent schedules subsumes the "Probability Matching" finding of mathematical learning theory, and both are equivalent to zero contingency between responses and consequences.

Avoidance Learning↗
PubMed1969

Temporal order judgement and reaction time.

A model which predicts judgment of the temporal order of stimuli from simple reaction time is proposed. Visual data show covariation of the two measures with luminance changes, and suggest that (i) temporal order judgments reflect a biased response criterion and (ii) the motor component of reaction time has little variability relative to variance in receptor system latency.

Humans↗
PubMed1967

Discriminated punishment: avoidable and unavoidable shock.

Warning stimuli for two punishment conditions were alternated with periods of appetitive responding by rats. In either warning stimulus, the first response produced a brief shock, terminated the stimulus, and started an interval during which the baseline appetitive schedule was in effect. Not responding resulted in stimuli of random duration, which terminated with a shock under one condition and without a shock under the other. Each subject was exposed to several shock intensities, with trials for the two conditions programmed during alternate portions of the session. In general, response frequency in the warning signal for either condition decreased with increasing intensity; however, at a given intensity, responding was more frequent in the stimulus invariably terminating with shock than in the stimulus terminating without shock when no response was made. The frequency difference was greatest at intensities intermediate between those producing minimal and maximal suppression.

Animals↗