The extinction of an aversion: Role of the interval between non-reinforced presentations of the averted stimulus

A toxiphobia conditioning paradigm was used to examine the relation between the intertrial interval (ITI) and the extinction of an aversion. The design employed was based upon that developed by Davis (1970) to study the relation between the ITI and the habituation of a response. After conditioning, the conditioned stimulus (CS) was presented on two occasions at times T1 and T2, and this interval (the ITI) was varied across groups. However, the interval from the CS exposure at T2 to the extinction test was common for all groups. On the test, ITIs of 6 to 24 hr were found to have promoted more extinction than ITIs of 0.5 hr with odour (Experiments 1a and b) and flavour (Experiment 1c) CSs. Further, this facilitation of extinction by the long ITIs compared to the short ones was not due to differences in the intervals between the initial CS exposure at T1 and the test (Experiment 2). The final experiment examined the relation between the ITI and extinction when different CSs were presented at T1 and T2. A short interval between the presentation of CS1 at T1 and the presentation of CS2 at T2 was found to have facilitated the extinction of the aversion to CS2 compared either to a long interval between these presentations or to the presentation of CS2 in the absence of a prior CS1 presentation. The results were discussed in terms of the model developed by Wagner (1981).     

The relation between auditory temporal interval processing and sequential stream segregation examined with stimulus laterality differences

In this study, we examine the effects of laterality differences between noise bursts on two objective measures of temporal interval processing (gap detection and temporal asymmetry detection) and one subjective measure of temporal organization (stream segregation). Noise bursts were lateralized by presentation to different ears or dichotic presentation with oppositely signed interaural level (ILD) or time (ITD) differences. Objective thresholds were strongly affected by ear-of-entry differences, were moderately affected by ILD differences, but were unaffected by ITD differences. Subjectively, A and B streams segregated well on the basis of ear-of-entry or ILD differences but segregated poorly on the basis of ITD differences. These results suggest that perceptual segregation may be driven more effectively by differential activation of the two ears (peripheral channeling) than by differences in perceived laterality.     

Audiovisual synchrony and temporal order judgments: effects of experimental method and stimulus type

When an audio-visual event is perceived in the natural environment, a physical delay will always occur between the arrival of the leading visual component and that of the trailing auditory component. This natural timing relationship suggests that the point of subjective simultaneity (PSS) should occur at an auditory delay greater than or equal to 0 msec. A review of the literature suggests that PSS estimates derived from a temporal order judgment (TOJ) task differ from those derived from a synchrony judgment (SJ) task, with (unnatural) auditory-leading PSS values reported mainly for the TOJ task. We report data from two stimulus types that differed in terms of complexity--namely, (1) a flash and a click and (2) a bouncing ball and an impact sound. The same participants judged the temporal order and synchrony of both stimulus types, using three experimental methods: (1) a TOJ task with two response categories ("audio first" or "video first"), (2) an SJ task with two response categories ("synchronous" or "asynchronous"; SJ2), and (3) an SJ task with three response categories ("audio first," "synchronous," or "video first"; SJ3). Both stimulus types produced correlated PSS estimates with the SJ tasks, but the estimates from the TOJ procedure were uncorrelated with those obtained from the SJ tasks. These results suggest that the SJ task should be preferred over the TOJ task when the primary interest is i n perceived audio-visualsynchrony.     

Effects of the temporal relationship of feedback and stimulus information upon discrimination-learning strategies

Second grade Ss and college students were tested under three conditions of the temporal relationship of feedback and stimulus information. In one condition (/+3) feedback was delivered immediately upon S's response while the stimuli were still in view. In another (/0) feedback was also immediate but stimuli were extinguished immediately upon S's response. In the third condition (/?3), stimuli were extinguished immediately upon response and feedback was delayed 3 sec. Major findings among the children were (a) Ss of all conditions coded information at the same (high) average efficiency, (b) Ss of conditions /0 and /?3 recoded with significantly less efficiency than those of /+3, and (c) Ss in condition /+3 manifested primarily efficient information-processing strategies, those in condition /0 showed intermediate performance, and those of condition /?3 showed relatively primitive stereotyped behavior. Among adult Ss performance was uniformly high with little effect on any response measure investigated.     

Relative judgments affect assessments of stimulus duration

Humans were trained on two independent temporal discriminations, with correct choice dependent on the initial stimulus duration. In Experiment 1, the durations were 1.0 and 4.0 sec, with one set of choice stimuli, and 2.0 and 8.0 sec, with a different set of choice stimuli. The 2.0- and 4.0-sec values were selected to be the geometric mean of the two values in the other discrimination. In Experiment 2, the durations were 2.0 and 5.0 sec for one discrimination and 3.5 and 6.5 sec for the other. The 3.5- and 5.0-sec values were selected to be the arithmetic mean of the two values in the other discrimination. In both experiments, participants showed evidence for relational coding of the duration pairs. That is, the test durations were selected to be at the presumed bisection point (i.e., they should have produced indifferent choice), but instead the shorter test duration from the longer duration pair produced a “short” bias (in both experiments), whereas the longer duration from the shorter duration pair produced a “long” bias (in the second experiment). Results were similar to those from Zentall, Weaver, and Clement (2004) with pigeons.     

Intervening stimulus effects on category judgments of duration

Auditory pulses (1,000 Hz) occurring between the 500-Hz bounding markers of durations being judged were varied in their position and number over three experiments which examined the effects of these factors on measures of amount of filled-duration illusion (FDI) and interduration discriminability. The results establish that the locus of the FDI is postattentive, since some of the incoming sensory information, selected on the basis of simple physical cues, can be excluded from further processing. FDI decreases both when the intervening stimuli come from a different source (earphone channel) to the marker stimuli and when they appear as part of an ongoing sequence of background pulses. Discrimination of durations containing intervening stimuli is enhanced if the filler events are placed such that repetitions of a given subinterval result. Thomas and Brown’s (1974) “chunking” model can account for the observed effects with the additional assumption that the error associated with encoding a given subinterval is sequentially modified as a function of number of recent encodings.     

On the interdependence of temporal and spatial judgments

Three experiments are reported on the tau and kappa effects, the dependence of judgments of distance upon duration (tau) and of judgments of duration upon distance (kappa). In Experiment 1, three lights in a horizontal sequence were used to define two temporal and two spatial intervals over a total duration of 160 msec. The subject was required to choose the shorter of either the two durations or the two distances. The results confirmed Collyer’s (1977) findings that the two effects are inconsistently observed across subjects when the display duration is brief. In Experiment 2, display duration was systematically manipulated from 160 to 1,500 msec. It is argued that relative temporal judgments should become easier as the total display duration is increased and that, hence, the kappa effect should become less marked. On the other hand, relative spatial judgments should become more difficult as the total duration of the display is increased, and the tau effect should become more marked. The data were in conformity with the hypothesis. In Experiment 3, data are presented for a tau experiment which fit the assumption that the effect depends upon a weighted average of distance and the expected distance which would be traversed in the given time at constant velocity.     

The effect of negative stimulus presentations on observing-response rates

Theories of observing differ in predicting whether or not a signal for absence of reinforcement (S−) is capable of reinforcing observing responses. Experiments in which S− was first removed from and then restored to the procedure have yielded mixed results. The present experiments suggest that failure to control for the direct effect of presenting S− may have been responsible. Pigeons and operant procedures were used. Experiment 1 showed that presentations of S−, even when not contingent on observing, can raise the rate of an observing response that was reinforced only by presentations of a signal (S+) that accompanied a schedule of food delivery. Experiment 2 showed that this effect resulted from bursts of responding that followed offsets of S−. Experiment 3 showed that, when the presence of S− was held constant, lower rates occurred when S− was dependent on, rather than independent of, observing. These results support theories that characterize S− as incapable of reinforcing observing responses.     

Intertrial interval as a contextual stimulus: further analysis of a novel asymmetry in temporal discrimination learning

Four experiments investigated discrimination learning when the duration of the intertrial interval (ITI) signaled whether or not the next conditional stimulus (CS) would be paired with food pellets. Rats received presentations of a 10-s CS separated half the time by long ITIs and half the time by short ITIs. When the long ITI signaled that the CS would be reinforced and the short interval signaled that it would not be (Long+/Short-), rats learned the discrimination readily. However, when the short ITI signaled that the CS would be reinforced and the long interval signaled that it would not (Short+/Long-), discrimination learning was much slower. Experiment 1 compared Long+/Short- and Short+/Long- discrimination learning with 16-min/4-min or 4-min/1-min ITI combinations. Experiment 2 found no evidence that Short+/Long- learning is inferior because the temporal cue corresponding to the short interval is ambiguous. Experiment 3 found no evidence that Short+/Long- learning is poor because the end of a long ITI signals a substantial reduction in delay to the next reinforcer. Long+/Short- learning may be faster than Short+/Long-because elapsing time involves exposure to a sequence of hypothetical stimulus elements (e.g., A then B), and feature-positive discriminations (AB+/A-) are learned quicker than feature-negative discriminations (A+/AB-). Consistent with this view, Experiment 4 found a robust feature-positive effect when sequentially presented CSs played the role of elements A and B.     

The repetition effect in time judgments is not a function of the intensity of the stimulus defining the interval: implications for an arousal theory

College students (N = 17 per group) estimated the durations of time intervals ranging from 8 to 20 sec. Intervals were defined by tones of 35, 55, and 75 db for each of three groups. The estimates of all groups declined across trials, but the degree of decline did not differ as a function of stimulus intensity. These data call into question the view that the repetition effect is attributable to a decrement in general arousal.     

Dissociations between reaction times and temporal order judgments: a diffusion model approach

A diffusion model for simple reaction time (RT) and temporal order judgment (TOJ) tasks was developed to account for a commonly observed dissociation between these 2 tasks: Most stimulus manipulations (e.g., intensity) have larger effects in RT tasks than in TOJ tasks. The model assumes that a detection criterion determines the level of sensory evidence needed to conclude that a stimulus has been presented. Analysis of the performance that would be achieved with different possible criterion settings revealed that performance was optimal with a lower criterion setting for the TOJ task than for the RT task. In addition, the model predicts that effects of stimulus manipulations should increase with the size of the detection criterion. Thus, the model suggests that commonly observed dissociations between RT and TOJ tasks may simply be due to performance optimization in the face of conflicting task demands.     

Cues produced by reward and nonreward and temporal cues influence responding in the intertrial interval and to the conditioned stimulus

Rats in a Pavlovian situation were trained under three different reward schedules, at either a 30 s or a 90 s intertrial interval (ITI): Consistent reward (C), 50% irregular reward (I), and single alternation of reward and nonrewarded trials (SA). Activity was recorded to the conditioned stimulus (CS) and in all 10 s bins in each ITI except the first 10 s bin. Responding increased progressively over the bins of the 90 s ITI indicating a role for temporal cues in the ITI. Single alternation patterning (SAP), more vigorous responding on rewarded than on nonrewarded trials, occurred in the ITI as well as to the CS and differed little at the 30 s and 90 s ITI. The occurrence of SAP to the CS and, as shown here for the first time, in the ITI along with the findings for the C and I schedules, indicate three matters of importance. First, along with other cues such as temporal cues, behavior is influenced by cues associated with reward and nonreward both in the ITI and when the CS is presented. Second, as the percentage of reward associated with these cues increases so too does vigor of responding. Finally, if the cues produced by reward events are memories the retrieval cues for such memories are present in the ITI as well as when the CS is presented. Considerations are advanced indicating that reward produced cues may influence responding in the Pavlovian situation not only under regular schedules such as the SA schedule, but under all schedules. Indeed, such cues may more validly signal reward and nonreward than the CS itself.     

Effect of stimulus configuration on spatial judgments in search tasks

Although children over one year of age are able to code spatial information with respect to objects other than the self, there are many instances in which the self is inappropriately used as a spatial referent by children between 2 and 4 years of age. L. G. Braine and R. A. Eder (1983, Developmental Psychology, 19, 45-55) found that, in a search task, the nature of the array influenced the spatial referent used by 2-year-old children. The present work investigated the effect of varying the number, size, and arrangement of boxes in the array. It was found that only the number of boxes defining the left and right sides of the array influenced performance; that is, multiple boxes were associated with the use of external objects as spatial referents. These results were interpreted as stemming from the tendency of young children to code the location of an object with respect to nearby objects. This tendency would lead to the use of adjacent boxes and environmental objects as spatial referents for the multiple-box side, and the use of the self as a spatial referent for the single-box side.