The effect of sequential dependencies on some signal detection parameters

The values of various sensitivity and response criterion parameters were calculated under different experimental conditions for both detection and recognition tasks. The effects of feedback and stimulus probability were found to be consistent with previous studies. When the values of the parameters were computed depending on the nature of the immediately preceding trial, the criterion parameters were found to be dependent on the identity of the preceding response, while those measuring sensitivity were dependent on its correctness. The dependence of the sensitivity parameters could be explained as an artifact of statistical bias, while the effect on the criterion parameters appears genuine. The nature of the phenomenon of statistical bias is discussed.     

The role of reinforcement in controlling sequential IRT dependencies

Sequential dependencies were investigated with two rats in a mixed and in a tandem differential-reinforcement-of-low-rate-responding schedule. In each schedule, 5-sec and 15-sec components were presented in fixed alternation. In the mixed schedule, a 5-sec interresponse time followed a 15-sec interresponse time and a 15-sec interresponse time followed a 5-sec interresponse time in predictable sequence. The correlation between prior and subsequent interresponse times, however, existed only when the prior interresponse time resulted in reinforcement. In the tandem schedule, an interresponse time greater than 5 sec in the differential-reinforcement-of-low-rate 5-sec component was not associated directly with reinforcement. One subject demonstrated sequential response patterns similar to those noted in the mixed schedule, even though the prior 5-sec interresponse time was not reinforced in the tandem schedule. The results indicate that the prior interresponse time length alone is not sufficient to influence the subsequent interresponse time length. Implications are, however, that a temporal response pattern arises when an interresponse interacts with schedule contingencies to control the interreinforcement interval.     

Cognitive factors affecting sequential dependencies in differential eyelid conditioning

Sequential dependencies were examined as a function of learning, masking, and subject factors in a two-stage differential eyelid conditioning experiment. In Stage 1, all subjects were differentially conditioned to two Vanderplas and Garvin (1959) forms. In Stage 2, the conditional stimuli (CSs) were one of eight words, four reinforced (CS+) and four unreinforced (CS?), with taxonomic category (animalsvs. musical instruments) as the discriminandum, and different subjects were given semantic, physical, or no additional CS processing tasks. The results showed sizeable and highly significant sequential dependencies in the form of greater conditional response probabilities when CS + as opposed to CS? trials were recently experienced. These effects decreased overtrials, were greater in the groups given additional processing loads, and were in some cases greater in C-form responders than in V-form responders and greater in subjects who were unable to verbalize the differential contingencies. It was concluded that the magnitude of sequential dependencies was inversely related to the subject’s awareness of the differential contingencies and/or ability to use the contingency information to respond appropriately to the CS cues.     

Identification of sequential dependencies in conversations: A Pascal program

A Pascal program that provides an analysis of the sequential dependencies between conversational events (e.g., speech acts) generated by two sources is described It produces z scores, chirsquare values, and confidence limits for the difference between estimated unconditional probabilities of the occurrence of selected events (valid events) and estimated conditional probabilities of these events following specified target events immediately (at Lag 1) and, if required, more distantly (at Lags 2, 3, etc.). Valid events and target events may be independently selected from the set of events generated by the first source, the second source, or both. Events not selected are ignored. The user may also elect to exclude the target event from the set of valid events (an adjustment for autocorrelation). The program is especially appropriate for conversational events because it does not assume that two events from the same category can never follow one another.     

Trial-to-trial sequential dependencies in a social and non-social Simon task

Recent research has shown that joint-action effects in a social Simon task provide a good index of action co-representation. The present study aimed to specify the mechanisms underlying joint action by considering trial-to-trial transitions. Using non-social stimuli, we assigned a Simon task to two participants. Each was responsible for only one of two possible responses. This task was performed alone (Individual go/nogo task) and in cooperation with another person who was sitting alongside (Joint go/nogo task). As a further control task, we added a Standard Simon task. Replicating previous findings (Sebanz et al. in Cognition 88:B11-B21, 2003), we found no spatial compatibility effect in the Individual go/nogo task but we did find one in the Joint go/nogo task. A more detailed analysis showed that a sequential modulation of the Simon effect was present in both the Joint and the Individual go/nogo tasks. We found reliable Simon effects in trials following Simon compatible trials not only in the Joint go/nogo task but also to a somewhat smaller extent in the Individual go/nogo task. For both these go/nogo tasks, sequential modulation effects were stronger for nogo/go transitions than for go/go transitions. This suggests that low-level feature binding and repetition mechanisms contribute to the social Simon effect related to the specific requirement not to respond on nogo trials.     

Target location probability effects in visual search: an effect of sequential dependencies

Target location probability was manipulated in a visual search task. When the target was twice as likely to appear on 1 side of the display as the other, manual button-press response times were faster (Experiment 1A) and first saccades were more frequently directed (Experiment 1B) to the more probable locations. When the target appeared with equal probability at each location in this search task, performance benefited from repetition of target location in the preceding trials (Experiment 2). When the trial sequence was constrained so that target location did not repeat within a series of 4 trials, there was no longer an advantage for more probable locations (Experiment 3). The authors conclude that the search benefits for more probable locations resulted from short-term target location repetitions.     

Implicit learning of second-, third-, and fourth-order adjacent and nonadjacent sequential dependencies

Serial reaction time (SRT) task studies have established that people can implicitly learn first- and second-order adjacent dependencies. Sequential confounds have made it impossible to draw conclusions regarding learning of nonadjacent dependencies and learning of third- and fourth-order adjacent dependencies. Addressing the confounds, the present study shows that people can implicitly learn second-, third-, and fourth-order adjacent and nonadjacent dependencies embedded in probabilistic sequences of target locations.     

Implicit learning of second-, third-, and fourth-order adjacent and nonadjacent sequential dependencies

Serial reaction time (SRT) task studies have established that people can implicitly learn first- and second-order adjacent dependencies. Sequential confounds have made it impossible to draw conclusions regarding learning of nonadjacent dependencies and learning of third- and fourth-order adjacent dependencies. Addressing the confounds, the present study shows that people can implicitly learn second-, third-, and fourth-order adjacent and nonadjacent dependencies embedded in probabilistic sequences of target locations.     

Mechanisms underlying dependencies of performance on stimulus history in a two-alternative forced-choice task

In choice reaction time tasks, response times and error rates demonstrate differential dependencies on the identities of up to four stimuli preceding the current one. Although the general profile of reaction times and error rates, when plotted against the stimulus histories, may seem idiosyncratic, we show that it can result from simple underlying mechanisms that take account of the occurrence of stimulus repetitions and alternations. Employing a simple connectionist model of a two-alternative forcedchoice task, we explored various combinations of repetition and alternation detection schemes in an attempt to account for empirical results from the literature and from our own studies. We found that certain combinations of the repetition and the alternation schemes provided good fits to the data, suggesting that simple mechanisms may serve to explain the complicated but highly reproducible higher order dependencies of task performance on stimulus history.     

On the relationship between memory and perception: sequential dependencies in recognition memory testing

Many models of recognition are derived from models originally applied to perception tasks, which assume that decisions from trial to trial are independent. While the independence assumption is violated for many perception tasks, we present the results of several experiments intended to relate memory and perception by exploring sequential dependencies in recognition. The findings from these experiments disconfirm the independence assumption for recognition memory. In addition, the pattern of sequential dependencies observed in recognition differs from that observed for many perception tasks. This suggests that sequential dependencies arise from mnemonic or perceptual processes and not from decision processes that should be common to memory and perception tasks.     

Critical bands and mixed-frequency scaling: sequential dependencies, equal-loudness contours, and power function exponents

Stimuli of random intensities and various but predictable frequencies were presented for repeated magnitude estimations on the same scale (mixed-frequency scaling). The frequencies for a particular judgment session were selected so that they lay either inside each other's critical bands or outside them. Contrastive dependencies of current magnitude estimation responses on previous stimuli of a different frequency were significantly affected by whether the two frequencies were inside or outside each other's critical bands, while assimilative dependencies were not. This reinforces the idea that such dependencies are sensory in nature and arise from a different mechanism than do the assimilative dependencies. Mixed-frequency scaling of loudness also gives rise to cross-frequency matching functions from which equal-loudness contours can be calculated. These contours calculated from the present judgments are similar to those produced from other methods, even when they are extrapolated to untested intensities. Power function exponents for loudness scaled in this way are larger for lower frequencies, as has been found in previous studies, and are consistent with the flattening of the calculated equal-loudness contours for low frequencies as intensity increases.     

Effects of observation cost on sequential search behavior

Sixty Ss participated individually in a search problem attempting to find a single target object located in one of several distinguishable regions. The search consisted of sampling observations with replacement from the various regions. Ss were told the prior probability of finding the target in a given region, the conditional miss probability that if the target is in a given region it will not be detected on a single observation there, and the cost per observation for each region. The effect of observation costs was investigated. Procedures devised for comparing actual and optimal search behavior showed that relative to the optimal policy Ss erred in the direction of maximizing detection probabilities rather than in the direction of minimizing the cost per observation, and that this error increased in magnitude the larger the differences among observation costs. A Markov model was tested and rejected. Implications of the study to visual search problems are discussed briefly.     

Effects of differences in timbre on sequential grouping

Differences in the timbre of sounds in a sequence can affect their perceptual organization. Using a performance measure, Hartmann and Johnson (1991) concluded that streaming could be predicted primarily by the extent to which sounds were passed by different peripheral channels. However, results from a rating task by Dannenbring and Bregman (1976) suggested that sounds in the same spectral region (passed by the same peripheral channels) can be allocated to different streams. In Experiment 1, it was found, using an interleaved melody task, that target sounds could be selected from distractors in the same spectral region more easily when they differed in timbre. This finding might result from primitive stream segregation or schema-driven selection, but not from peripheral channeling. In Experiment 2, a rhythm discrimination task was used, requiring the sounds to be integrated for good performance. Differences in timbre impaired performance, indicating the occurrence of primitive stream segregation.     

Contextual dependencies: Influence on response latency

Abstract

The present experiments were designed to examine the influence of contextual stimuli on perceptual-motor performance. Experiment 1 revealed that contextual dependencies can develop for simple perceptual-motor tasks. Furthermore, the extent of the dependency is mediated in part by whether the contextual information is removed or replaced with alternative contextual information at the time of test. Data from Experiments 2 and 3 showed that manipulating the potency of incidental contextual stimuli results in a systematic decrement or increment in subsequent performance, depending on whether the contextual stimuli during the test were changed or reinstated. To date, such an orderly influence of contextual stimuli is more commonly demonstrated in the animal learning literature than with human experimentation.     

The effect of mental practice on performance in a sequential reaction time task

The effect of mental practice on performance in a dot-location RT task was investigated. Participants (N = 40) were required either to mentally practice, physically practice, or do no practice on an RT task in which the signals appeared in a repeating sequence. Correct mental practice, as opposed to incorrect mental practice and no practice, was predicted to have a positive (enhancing) effect on performance of the RT task. Despite previous evidence that mental rehearsal does enhance performance in many perceptual-motor tasks, neither correct nor incorrect mental rehearsal affected subsequent sequence learning; that is, no mental practice effect was observed. That surprising result is discussed in terms of motivational, psychoneuromuscular, separate memory systems, and transfer-appropriate processing explanations of mental practice.