Feedback effects on sequential ordering in humans

Under various feedback conditions, 38 college undergraduates were asked to rearrange abstract graphic characters on a computer screen, placing them in arbitrarily designated “correct” sequences. Two sets of seven horizontally arrayed stimuli were used. In Experiment 1, subjects in Group 1 learned to arrange the first set under Selection Feedback in which a “+” appeared above each character after it was selected in the correct order and to arrange the second set under Order Feedback in which a correct response produced a copy of the character in its correct ordinal position at the top of the screen. For Group 2 the order of these conditions was reversed. In Experiment 2, for subjects in Group 3, correct responses produced neither of these types of feedback. Subjects in Group 4 received Order Feedback only until the first set was correctly ordered once. Order Feedback was more effective than Selection Feedback during initial acquisition of the first set but not during maintenance; no differences were found for the second set. Only 2 of 9 subjects successfully put the characters in correct sequential order under the No Feedback condition. When, in Experiment 2, Order Feedback was eliminated after the first correctly arranged sequence, the steady-state criteria were met more slowly than in Experiment 1.     

Sequential responding and planning in capuchin monkeys (Cebus apella)

Previous experiments have assessed planning during sequential responding to computer generated stimuli by Old World nonhuman primates including chimpanzees and rhesus macaques. However, no such assessment has been made with a New World primate species. Capuchin monkeys (Cebus apella) are an interesting test case for assessing the distribution of cognitive processes in the Order Primates because they sometimes show proficiency in tasks also mastered by apes and Old World monkeys, but in other cases fail to match the proficiency of those other species. In two experiments, eight capuchin monkeys selected five arbitrary stimuli in distinct locations on a computer monitor in a learned sequence. In Experiment 1, shift trials occurred in which the second and third stimuli were transposed when the first stimulus was selected by the animal. In Experiment 2, mask trials occurred in which all remaining stimuli were masked after the monkey selected the first stimulus. Monkeys made more mistakes on trials in which the locations of the second and third stimuli were interchanged than on trials in which locations were not interchanged, suggesting they had already planned to select a location that no longer contained the correct stimulus. When mask trials occurred, monkeys performed at levels significantly better than chance, but their performance exceeded chance levels only for the first and the second selections on a trial. These data indicate that capuchin monkeys performed very similarly to chimpanzees and rhesus monkeys and appeared to plan their selection sequences during the computerized task, but only to a limited degree.     

Teaching serial position sequences to monkeys with a delayed matching-to-sample procedure

Comparison was made of two methods for training monkeys to “observe” a two-member serial position sequence by pressing two consecutively lighted keys and then to “report” the sequence by pressing the same two keys in the same order but without the lights. A fading technique involving gradual elimination of brightness cues from “reporting” keys was found more effective than a no-fading procedure in which the cues remained bright during training and then were suddenly removed. Animals that failed to learn to report a new sequence with the no-fading procedure sometimes developed behavior incompatible with that desired. They made repeated and specific errors that prematurely terminated trials of the sequence to-be-learned, even though the correct key was cued by a bright light. They behaved appropriately, however, on succeeding trials of other sequences. Thus, the errors were followed by trials on which reinforcement occurred. Manipulation of this contingency indicated its importance in maintaining the stereotyped error patterns.     

Analysis of discriminative control by social behavioral stimuli

Visual discriminative control of the behavior of one rat by the behavior of another was studied in a two-compartment chamber. Each rat's compartment had a food cup and two response keys arranged vertically next to the clear partition that separated the two rats. Illumination of the leader's key lights signaled a “search” period when a response by the leader on the unsignaled and randomly selected correct key for that trial illuminated the follower's keys. Then, a response by the follower on the corresponding key was reinforced, or a response on the incorrect key terminated the trial without reinforcement. Accuracy of following the leader increased to 85% within 15 sessions. Blocking the view of the leader reduced accuracy but not to chance levels. Apparent control by visual behavioral stimuli was also affected by auditory stimuli and a correction procedure. When white noise eliminated auditory cues, social learning was not acquired as fast nor as completely. A reductionistic position holds that behavioral stimuli are the same as nonsocial stimuli; however, that does not mean that they do not require any separate treatment. Behavioral stimuli are usually more variable than nonsocial stimuli, and further study is required to disentangle behavioral and nonsocial contributions to the stimulus control of social interactions.     

Does a sensory processing deficit explain counting accuracy on rapid visual sequencing tasks in adults with and without dyslexia?

The experiments conducted aimed to investigate whether reduced accuracy when counting stimuli presented in rapid temporal sequence in adults with dyslexia could be explained by a sensory processing deficit, a general slowing in processing speed or difficulties shifting attention between stimuli. To achieve these aims, the influence of the inter-stimulus interval (ISI), stimulus duration, and sequence length were evaluated in two experiments. In the first that used skilled readers only, significantly more errors were found with presentation of long sequences when the ISI or stimulus durations were short. Experiment 2 used a wider range of ISIs and stimulus durations. Compared to skilled readers, a group with dyslexia had reduced accuracy on two-stimulus sequences when the ISI was short, but not when the ISI was long. Although reduced accuracy was found on all short and long sequences by the group with dyslexia, when performance on two-stimulus sequences was used as an index of sensory processing efficiency and controlled, group differences were found with presentation of stimuli of short duration only. We concluded that continuous, repetitive stimulation to the same visual area can produce a capacity limitation on rapid counting tasks in all readers when the ISIs or stimulus durations are short. While reduced accuracy on rapid sequential counting tasks can be explained by a sensory processing deficit when the stimulus duration is long, slower processing speed in the group with dyslexia explains the greater inaccuracy found as sequence length is increased when the stimulus duration is short.     

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.     

Sequential reacquisition as a function of timeout from avoidance

Rats learned to reacquire four similar three-member response sequences. Each sequence member was associated with a different response lever, and the correct sequence of levers (i.e., 3-1-2, 2-1-3, 1-3-2, and 2-3-1) changed each session. The first two correct responses of each sequence postponed shock for a fixed period of time. The third correct response initiated a signalled timeout from avoidance. Incorrect responses did not affect the shock interval or reset the sequence. The effects of manipulating timeout duration on the sequential reacquisition baseline were investigated. All subjects displayed biphasic reacquisition performances similar to those controlled by food. The phases were characterized by an initial increase in accuracy, which reached a stable level during the latter portion of each session. Timeout duration affected rate of sequence completion and shock density, but not percentage of errors. Rate of sequence completion was fastest with intermediate timeouts (15 to 60 sec), and slowest with extreme durations (1 or 120 sec). Shock densities peaked with extreme durations and were at minimum with intermediate timeout values. The percentage of errors was the same across timeout durations. These data extend the generality of sequential reacquisition as a procedure for studying learning, and demonstrate timeout from avoidance to be a controlling variable.     

Intertrial sources of stimulus control and delayed matching-to-sample performance in humans

Two experiments compared delayed matching-to-sample (DMTS) accuracy under 2 procedures in adults with mental retardation. In the trial-unique procedure, every trial in a session contained different stimuli. Thus, comparison stimuli that were correct on one trial were never incorrect on other trials in that session (or vice versa). In the 2-sample DMTS procedure, the same 2 comparison stimuli were presented on each trial, and their function changed quasi-randomly across trials conditional upon the sample stimulus. Across 2 experiments, 7 of 8 subjects showed the highest overall accuracy under the trial-unique procedure, and no subject showed consistently higher accuracy under the 2-sample procedure. Negative, exponential decay functions fit to logit p values showed that this difference was due largely to the steeper delay-mediated decline in sample control for the 2-sample procedure. Stimulus-control analyses indicated that, under the 2-sample procedure, the selection of the comparison stimulus on Trial N was often controlled by the comparison stimulus selection on Trial N-1 rather than the Trial-N sample stimulus. This source of competing stimulus control is not present in trial-unique procedures. Experiment 2 manipulated intertrial interval duration. There was a small but consistent increase in accuracy as a function of intertrial interval duration under the 2-sample procedure, but not under the trial-unique procedure.     

Exploring the perceptual biases associated with believing and disbelieving in paranormal phenomena

Ninety-five participants (32 believers, 30 disbelievers and 33 neutral believers in the paranormal) participated in an experiment comprising one visual and one auditory block of trials. Each block included one ESP, two degraded stimuli and one random trial. Each trial included 8 screens or epochs of “random” noise. Participants entered a guess if they perceived a stimulus or changed their mind about stimulus identity, rated guesses for confidence and made notes during each trial. Believers and disbelievers did not differ in the number of guesses made, or in their ability to detect degraded stimuli. Believers displayed a trend toward making faster guesses for some conditions and significantly higher confidence and more misidentifications concerning guesses than disbelievers. Guesses, misidentifications and faster response latencies were generally more likely in the visual than auditory conditions. ESP performance was no different from chance. ESP performance did not differ between belief groups or sensory modalities.     

Social intuition as a form of implicit learning: Sequences of body movements are learned less explicitly than letter sequences

In the current paper, we first evaluate the suitability of traditional serial reaction time (SRT) and artificial grammar learning (AGL) experiments for measuring implicit learning of social signals. We then report the results of a novel sequence learning task which combines aspects of the SRT and AGL paradigms to meet our suggested criteria for how implicit learning experiments can be adapted to increase their relevance to situations of social intuition. The sequences followed standard finite-state grammars. Sequence learning and consciousness of acquired knowledge were compared between 2 groups of 24 participants viewing either sequences of individually presented letters or sequences of body-posture pictures, which were described as series of yoga movements. Participants in both conditions showed above-chance classification accuracy, indicating that sequence learning had occurred in both stimulus conditions. This shows that sequence learning can still be found when learning procedures reflect the characteristics of social intuition. Rule awareness was measured using trial-by-trial evaluation of decision strategy (Dienes & Scott, 2005; Scott & Dienes, 2008). For letters, sequence classification was best on trials where participants reported responding on the basis of explicit rules or memory, indicating some explicit learning in this condition. For body-posture, classification was not above chance on these types of trial, but instead showed a trend to be best on those trials where participants reported that their responses were based on intuition, familiarity, or random choice, suggesting that learning was more implicit. Results therefore indicate that the use of traditional stimuli in research on sequence learning might underestimate the extent to which learning is implicit in domains such as social learning, contributing to ongoing debate about levels of conscious awareness in implicit learning.     

Reinforcer frequency and restricted stimulus control.

Stimulus control was evaluated in 3 individuals with moderate to severe mental retardation by delayed identity matching-to-sample procedures that presented either one or two discrete forms as sample stimuli on each trial. On pretests, accuracy scores on one-sample trials were uniformly high. On two-sample trials, the correct stimulus (i.e., the one that subsequently appeared in the comparison array) varied unpredictably, and accuracy scores were substantially lower, suggesting that both sample stimuli did not exert stimulus control on every trial. Subjects were then given training sessions with the one-sample task and with a new set of four stimuli. For two of the stimuli, correct matching responses were followed by reinforcers on a variable-ratio schedule that led to a high reinforcer rate. For the other two stimuli, correct responses were followed by reinforcers on a variable-ratio schedule that led to a substantially lower reinforcer rate. Results on two-sample tests that followed showed that (a) on trials in which comparison arrays consisted of one high reinforcer-rate and one low reinforcer-rate stimulus, subjects most often selected the high-rate stimulus; and (b) on trials in which the comparison arrays were either two high reinforcer-rate stimuli or two low reinforcer-rate stimuli and the samples were one high reinforcer- and one low reinforcer-rate stimulus, accuracy was higher on trials with the high-rate comparisons. These results indicate that the frequency of stimulus control by high reinforcer-rate samples was greater than that by low reinforcer-rate samples. Following more training with the one-sample task and reversed reinforcement schedules for all stimuli, the differences in stimulus control frequencies on two-sample tests also reversed. These results demonstrate experimental control by reinforcement contingencies of which of two sample stimuli controlled selections in the two-sample task. The procedures and results may prove to be relevant for understanding restricted stimulus control and stimulus overselectivity.     

CONSTRUCTED-RESPONSE MATCHING TO SAMPLE AND SPELLING INSTRUCTION

The development of interactive programmed instruction using a microcomputer as a teaching machine is described. The program applied a constructed-response matching-to-sample procedure to computer-assisted spelling instruction and review. On each trial, subjects were presented with a sample stimulus and a choice pool consisting of 10 individual letters. In initial training, sample stimuli were arrays of letters, and subjects were taught to construct identical arrays by touching the matching letters in the choice pool. After generalized constructed-response identity matching was established, pictures (line drawings) of common objects were presented as samples. At first, correct spelling was prompted by also presenting the printed name to be “copied” via identity matching; then the prompts were faded out. The program was implemented with 2 mentally retarded individuals. Assessment trials determined appropriate words for training. Correct spelling was established via the prompt-fading procedure; training trials were interspersed among baseline trials that reviewed and maintained spelling of previously learned words. As new words were learned, they were added to a cumulative baseline to generate an individualized review and practice battery for each subject.     

Evidence for gating of direct response activation in the Simon task

TheSimon effect denotes faster responses when the task-irrelevant stimulus position corresponds to the response position than when it does not. Accounts of this effect assume that stimulus position automatically activates a spatially corresponding response while the correct response is being computed. Yet the Simon effect has been found to be reduced after noncorresponding trials. Some authors have interpreted these sequential modulations of the Simon effect as evidence for a mechanism gating positionbased response activation. Alternatively, sequential modulations have been explained in terms of feature-integration processes, which depend upon the fact that different sequences of spatial-correspondence conditions covary with different degrees of feature overlap between subsequent trials. The present study investigates whether sequential modulations of the Simon effect can occur when feature overlap in the different conditions is the same. Therefore, a Simon task with four stimulus positions and two response positions was used. Sequential modulations of the Simon effect were found in trial sequences with constant amounts of feature overlap between trials. Although the feature-integration account cannot explain this result, it is consistent with the idea of a gating (i.e., cognitive control) mechanism.     

Effects of reinforcement scheduling on simultaneous discrimination performance

Pigeons were trained on a discrete-trials, simultaneous discrimination procedure, with confusable stimuli such that asymptotic performance was about 85% correct. Trials were terminated if no response occurred within 2 sec of stimulus onset, so that probability of responding was free to vary. The schedule of reinforcement for correct responses was varied, with the following results: (1) there was no relation between frequency of reinforcement and accuracy of responding. (2) In extinction, the probability of responding fell to low levels, but accuracy remained roughly constant. (3) When reinforcement was available after a fixed number of trials or after a fixed number of correct responses, the probability of responding increased with successive trials after reinforcement, but accuracy was generally constant. (4) When every fifth correct response was reinforced, accuracy decreased immediately after reinforcement if the birds were required to respond on every trial.     

Sequential effects in absolute judgments of loudness

The effects of preceding stimuli on the judgments of current stimuli were examined in a study using absolute judgments of loudness with feedback. It was found that the response on a given trial was dependent on the stimuli in the preceding sequence of at least five trials. Both assimilation and contrast effects were observed. The form of the dependency of a response on a prior stimulus was a function of the ordinal position of the stimulus in the preceding sequence of trials. The stimulus on the immediately preceding trial had an assimilative effect on the response and preceding stimuli two to five trials removed all showed a contrast effect on a given response. The extent to which these preceding stimuli contributed to the contrast effect was an increasing function of their recency. The reversal of the dependency of the response, from assimilation to the stimulus one trial back, to contrast with the stimuli two and more trials back, indicates a unique function of the immediately preceding stimulus in this task. Since there was a reduction in the variance of responses to those stimuli similar in value to the immediately preceding stimulus, it is proposed that the stimulus and feedback on the last trial were remembered and used asa standardin judging the presented stimulus. A model is presented in which it is assumed that the memory of the magnitude of the immediately preceding stimulus is contaminated in specified ways by prior stimuli in the series. The empirical findings of assimilation and contrastare expected consequences of the proposed memorial processes.     

背景颜色对一致性序列效应的调节

为满足迅速变化的环境要求,个体需要快速灵活地调整认知加工策略。背景颜色是一个重要的环境因素,它能够影响人的认知和行为表现。然而,背景颜色对认知控制在线调整的影响,是一个关键但又被忽略的问题。为解决这个问题,本研究采用字母flanker任务,考察了灰色、蓝色和红色背景条件下的一致性序列效应。结果发现,蓝色背景下的一致性序列效应不显著,而灰色和红色背景下得到了显著的一致性序列效应;此外,在这三种颜色背景下,flanker干扰效应无显著差异。这些结果说明,蓝色背景影响一致性序列效应,但干扰效应不受背景颜色的调节。当前的研究首次揭示了背景颜色对认知控制在线调整的影响,也进一步加深了我们对一致性序列效应的理解。     

The base-rate fallacy in the context of sequential categories

Three experiments assessed base-rate utilization in a paradigm in which the relevant categories of the population were trials in sequences of variable length. In one version of stimulus materials, for example, a trial was represented by a toss of a coin, and a sequence was a series of coin tosses. Since each described sequence was to end upon the scoring of a “hit” in any trial, the likelihood of a trial’s being attempted was a decreasing function of its position in the sequence. Subjects who estimated the particular trial upon which the hit in a sequence was most likely to occur showed a significant tendency to ignore the probable higher prevalence—the greater base rate— of early trials in the overall population of atttempts, typically estimating that the hit in the sequence was equally likely on any trial. This tendency, however, was modified by the specific problem context. In all experiments, significantly more normatively correct estimates were made in the coin context, in which the disparity between base rates of early trials and later trials was most pronounced. Although subjects in the third experiment who had previously taken a statistics course displayed superior performance on the coin problem, there was no evidence of transfer of this superiority to another context. These results are interpreted within the theoretical framework of the base-rate fallacy. In particular, the article discusses implications of the finding that general base rates may be ignored even in the absence of specific diagnostic indicators.     

Role of action observation and action in sequence learning and coding

A complex sequence learning task was used to determine if the type of coding acquired through physical practice (PP), observation of the stimulus (Obs-S), or observation of stimulus and action (Obs-SA) differs between conditions and whether the type of observation influences subsequent learning of the task when physical practice was permitted. Participants in the Obs-S group were permitted to watch the sequentially illuminated stimuli on the screen. In the Obs-SA group participants could see both flexion-extension movements of the model's arm performing the sequence and the sequentially illuminated stimuli on the screen. Participants in the PP group actually performed the 16-element sequence with their dominant right arm. Delayed retention tests and two inter-manual transfer tests were completed following each of two acquisition sessions. First, the data indicated that learning the sequence structure, as revealed by response time per element, occurred similarly irrespective of the initial practice condition. Secondly, the movement sequence appeared to be coded in abstract visual-spatial coordinates resulting in effector-independent performance. Finally, observing the model's action and sequential stimuli allows participants to transfer the perceived aspects of the movement sequence into efficient coordination patterns when additional physical practice is permitted.     

Oddity learning by African dwarf goats ( Capra hircus)

Seventeen African dwarf goats (adult females) were trained on oddity tasks using an automated learning device. One odd stimulus and three identical nonodd stimuli were presented on a screen divided into four sectors; the sector for the odd stimulus was varied pseudorandomly. Responses to the odd stimulus were deemed to be correct and were reinforced with food. In phase 1, the goats were trained on eight stimulus configurations. From trial to trial the odd discriminandum was either a + symbol or the letter S, and the nonodd discriminandum was the symbol not used as the odd one. In phase 2, the animals were similarly trained using an unfilled triangle or a filled (i.e., solid black) circle. In phase 3, three new discriminanda were used, an unfilled, small circle with radiating lines, an unfilled heart-shaped symbol, and an unfilled oval; which of the three discriminanda was odd and nonodd was varied from trial to trial. Following these training phases, a transfer test was given, which involved 24 new discriminanda sets. These were presented twice for a total of 48 transfer test trials. Results early in training showed approximately 25% correct, which might be expected by chance in a four-choice task. After 500-2,000 trials, results improved to approximately 40-44% correct. The best-performing subject reached 60-80% correct during training. On the transfer test, this subject had 47.9% correct and that significantly exceeded 25% expected by chance. This finding suggests that some exceptional individuals of African dwarf goats are capable of learning the oddity concept.     

A procedure for generating differential "sample" responding without different exteroceptive stimuli

Sidman (1994, 2000) suggested that responses as well as stimuli can join equivalence classes, a hypothesis difficult to test because differential responding typically requires different stimuli. The present experiments describe a procedure with pigeons that avoids this potential confounding effect. In Experiment 1, spacing two responses 3 s apart (a differential-reinforcement-of-low-rate [DRL] schedule) to a white stimulus on some trials produced food or the comparison stimuli in a matching task, whereas pecking 10 or more times with no temporal restrictions (a fixed-ratio [FR] schedule) produced the same effect on other trials. Completing the alternative (unscheduled) requirement terminated the white stimulus and repeated the trial. Following such errors, pigeons learned to switch to the alternative response pattern on the repeat trials. In addition, the correct response pattern functioned as a conditional cue for comparison choice. In Experiment 2, mixed DRL-FR training was preceded by two-sample/two-alternative matching-to-sample with DRL and FR sample-response requirements. In a subsequent transfer test in which the correct response pattern to white served as the sample, pigeons preferentially chose the comparison previously reinforced following that pattern in the baseline task. This "unsignaled response" procedure may be useful for assessing whether differential responses can be members of acquired equivalence classes.