Alternative theories of concept identification among older adults

The purpose of the present experiment was to investigate some predictions of hypothesis testing and S-R association (frequency) theories regarding memory for intratrial events on a conjunctive concept-identification task. They have received extensive study with young adults but not with older subjects. The individual events under investigation were feedback, responses, hypotheses, and stimuli. Hypothesis-testing theory requires subjects to retain information concerning the correct hypothesis from one trial to the next whereas frequency does not. 75 subjects (60-70 yr. old) participated in the study. Subjects had difficulty in recalling the correct hypothesis stated on previous trials. These errors occurred on problems with negative response trials, not with incorrect feedback. The results contradict predictions based on hypothesis-testing models but are consistent with frequency theory. Unlike in the studies based on younger adults, present subjects did not recall the hypothesis very well under the conditions in which hypothesis testing was made part of the primary task.     

Stress effects on affiliation preferences among subjects possessing the type A coronary-prone behavior pattern

An experiment tested the hypothesis that when subjects who display the Type A coronary-prone behavior pattern are placed under stress, they prefer to wait for the stressful event with others, but desire to work under stress alone. One half of 25 Type A and 25 Type B (non-coronary-prone) subjects were told that they would receive painful electric shock while working on a mental task, while the other one half were told that they would receive subliminal stimulation. Both groups were then given the choice of waiting for the event with others or alone and the choice of working on the task alone, in the company of others, or in a leader-directed group. The results showed that Type As relative to Type Bs tended to wait in the company of others regardless of threat level, but displayed a marked preference to work alone under high threat. This decision to work alone was not influenced by waiting preference. Subsequent correlational studies showed that coronary patients (n = 40) reported a greater preference for working alone when under pressure than matched controls (n = 40), as did Type A college students (77% vs. 14% for Type Bs) when asked their preference within the context of the structured interview that is used to assess the Type A pattern. The significance of the findings for increasing the understanding of affiliative preferences and coronary-prone behavior are discussed.     

Assessment and selection of paired associate strategies: A developmental study

First, third, and fifth graders who had been instructed to use an interaction strategy and a repetition strategy on two separate paired associate tasks were asked on which task they had remembered better and why. Subjects were then given another paired associate task and told they could use any way they wanted to remember. Memory performance was better when the interaction strategy was used than when the repetition strategy was used. A significant majority of third and fifth graders correctly judged which task they had performed better on, and the number of subjects doing so increased with grade. Only among fifth graders, did the majority of subjects explain their judgments by referring to the use of the interaction strategy. Use of the interaction strategy on Task 3 did not increase with grade but was shown by a significant majority of first and fifth graders. Use of the interaction strategy on Task 3 was more frequent among subjects who referred to the use of the interaction strategy in explaining their choice of their more successful task than among those who did not.     

The Effect of Perceived Control on Risk Taking1

The experiment investigates the effect of perceived control on risk taking in a dynamic, everyday task. Using established and validated video simulation techniques, the risk-taking preferences for 96 drivers were measured for a range of driving activities (speed choice, following distance, gap acceptance, and overtaking). The perceived control manipulation was as follows: Half of the participants were told to imagine they were driving the vehicle, and the other half were told to imagine they were passengers. Those who were told to imagine they were driving chose significantly faster speeds than did those who were told to imagine they were passengers. Differences for the other risk-taking measures were not significant. For speed choice, it could be argued that an illusion of control was in operation, such that those who were in control (i.e., drivers) were comfortable with a higher level of risk than those who were not in control (i.e., passengers).     

IMPULSIVITY AND INHIBITORY CONTROL

Abstract— We report an experiment testing the hypothesis that impulsive behavior reflects a deficit in the ability to inhibit prepotent responses Specifically, we examined whether impulsive people respond more slowly to signals to inhibit (stop signals) than non-impulsive people In this experiment, 136 undergraduate students completed an impulsivity questionnaire and then participated in a stop-signal experiment, in which they performed a choice reaction time (go) task and were asked to inhibit their responses to the go task when they heard a stop signal The delay between the go signal and the stop signal was determined by a tracking procedure designed to allow subjects to inhibit on 50% of the stop-signal trials. Reaction time to the go signal did not vary with impulsivity, but estimated stop-signal reaction time was longer in more impulsive subjects, consistent with the hypothesis and consistent with results from populations with pathological problems with impulse control.     

Rehearsal strategy as a function of recall expectation

The subjects were divided into three groups with respect to their expectations concerning a recall task given after the final trial of the usual STM distractor procedure. Group 1 were told only that they would have to recall during each trial's recall interval, thus did not expect to have to recall again. Group 2 were told that they would have to recall all the words presented in the experiment at the end of the last trial, in addition to the trial-by-trial recall. Group 3 were told only that they would have to recall after all words had been presented and they sat passively through the presentation trials. In addition to their recall expectations, half of the subjects in each group received a 2-s presentation and half received a 5-s presentation interval. It was found that the length of the presentation interval had an effect on the number of words recalled at the end of all trials, but recall expectancy did not. However, expectancy did determine the rehearsal strategies of subjects and hence the serial positions from which items were recalled.     

Innocent but proven guilty: Eliciting internalized false confessions using doctored‐video evidence

More powerful computers and affordable digital‐video equipment means that desktop‐video editing is now accessible and popular. In two experiments, we investigated whether seeing fake‐video evidence, or simply being told that video evidence exists, could lead people to believe they committed an act they never did. Subjects completed a computerized gambling task, and when they returned later the same day, we falsely accused them of cheating on the task. All of the subjects were told that incriminating video evidence existed, and half were also exposed to a fake video. See‐video subjects were more likely to confess without resistance, and to internalize the act than told‐video subjects, and see‐video subjects tended to confabulate details more often than told‐video subjects. We offer a metacognitive‐based account of our results. Copyright © 2008 John Wiley & Sons, Ltd.     

Can fabricated evidence induce false eyewitness testimony?

False information can influence people's beliefs and memories. But can fabricated evidence induce individuals to accuse another person of doing something they never did? We examined whether exposure to a fabricated video could produce false eyewitness testimony. Subjects completed a gambling task alongside a confederate subject, and later we falsely told subjects that their partner had cheated on the task. Some subjects viewed a digitally manipulated video of their partner cheating; some were told that video evidence of the cheating exists; and others were not told anything about video evidence. Subjects were asked to sign a statement confirming that they witnessed the incident and that their corroboration could be used in disciplinary action against the accused. See‐video subjects were three times more likely to sign the statement than Told‐video and Control subjects. Fabricated evidence may, indeed, produce false eyewitness testimony; we discuss probable cognitive mechanisms. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluency versus conscious recollection in the word completion performance of amnesic patients

To examine the relative contribution of fluency and recollection to the word completion performance of amnesics, we administered a task in which patients were told specifically not to utilize previously presented words during stem completion (an Exclusion condition). This condition was contrasted with a standard word completion task in which patients were encouraged simply to complete the stem with the first word that came to mind (an Inclusion condition). Since the exclusion condition necessitated controlled respecification of the initial presentation, it was hypothesized that amnesics would be less able than controls to exclude study list items. Consistent with this hypothesis, the results indicated that the amnesics' performance, unlike that of the alcoholic controls, did not significantly differ as a function of task condition. To examine whether amnesics' conscious recollection could be enhanced, Experiment 2 presented the study list five times. The amnesics now were able to exclude a significant number of items from the study list; however, they still did so considerably less frequently than alcoholic controls. For the alcoholic controls, increasing the number of study trials had little additional effect on their exclusion performance, but it significantly enhanced their inclusion performance. Taken together, these findings suggest that for control subjects, word completion performance is likely mediated by a combination of fluency and recollection, while for amnesic patients, performance is almost exclusively based on the fluency with which an item comes to mind.     

On the dominance of unidimensional rules in unsupervised categorization.

In several experiments, observers tried to categorize stimuli constructed from two separable stimulus dimensions in the absence of any trial-by-trial feedback. In all of the experiments, the observers were told the number of categories (i.e., two), they were told that perfect accuracy was possible, and they were given extensive experience in the task (i.e., 800 trials). When the boundary separating the contrasting categories was unidimensional, the accuracy of all observers improved significantly over blocks (i.e., learning occurred), and all observers eventually responded optimally. When the optimal boundary was diagonal, none of the observers responded optimally. Instead they all used some sort of suboptimal unidimensional rule. In a separate feedback experiment, all observers responded optimally in the diagonal condition. These results contrast with those for supervised category learning; they support the hypothesis that in the absence of feedback, people are constrained to use unidimensional rules.     

On the dominance of unidimensional rules in unsupervised categorization

In several experiments, observers tried to categorize stimuli constructed from two separable stimulus dimensions in the absence of any trial-by-trial feedback. In all of the experiments, the observers were told the number of categories (i.e., two), they were told that perfect accuracy was possible, and they were given extensive experience in the task (i.e., 800 trials). When the boundary separating the contrasting categories was umdimensional, the accuracy of all observers improved significantly over blocks (i.e., learning occurred), and all observers eventually responded optimally. When the optimal boundary was diagonal, none of the observers responded optimally. Instead they all used some sort of suboptimal unidimensional rule. In a separate feedback experiment, all observers responded optimally in the diagonal condition. These results contrast with those for supervised category learning; they support the hypothesis that in the absence of feedback, people are constrained to use unidimensional rules.     

The form of analog size information in memory

The information used to choose the larger of two objects from memory was investigated in two experiments that compared the effects of a number of variables on the performance of subjects who either were instructed to use imagery in the comparison task or were not so instructed. Subjects instructed to use imagery could perform the task more quickly if they prepared themselves with an image of one of the objects at its normal size, rather than with an image that was abnormally big or small, or no image at all. Such subjects were also subject to substantial selective interference when asked to simultaneously maintain irrelevant images of digits. In contrast, when subjects were not specifically instructed to use imagery to reach their decisions, an initial image at normal size did not produce significantly faster decisions than no image, or a large or small image congruent with the correct decision. The selective interference created by simultaneously imaging digits was reduced for subjects not told to base their size comparisons on imagery. The difficulty of the size discrimination did not interact significantly with any other variable. The results suggest that subjects, unless specifically instructed to use imagery, can compare the size of objects in memory using information more abstract than visual imagery.     

The effect of prediction accuracy on choice reaction time

In this study, we examined the effect of prediction accuracy on reaction time (RT). Subjects performed on three blocks of choice RT trials, all of which involved the mapping of four stimuli (red, green, 1, or 0) onto two response keys. The subjects were told that the four stimuli were equally probable and that their task was to respond to each stimulus onset by pressing the correct key. In one block (stimulus-prediction), the subjects predicted, prior to each trial, the precise stimulus that would appear. In a second block (category-prediction), the subjects predicted the category of the stimulus (i.e., color or digit) that would appear. In a third block (no-prediction), the subjects simply responded to each stimulus without making a prior prediction. In the stimulus-prediction block, RT was faster for correct predictions than for incorrect predictions. In addition, RT was faster on trials in which an incorrect prediction involved the correct category than on trials in which it involved the incorrect category: that is, a "half-wrong" prediction was better than an "all-wrong" prediction. In the category-prediction block, RT was faster when the stimulus category was predicted correctly than when it was not. There was little evidence of a response-facilitation contribution to the correct-prediction effect. These results permit inferences concerning the encoding and organization of information in memory.     

Rate of processing and judgment of response speed: comparing the effects of alcohol and practice

Both alcohol and practice affect choice reaction time. The present study was conducted to investigate the possibility that impairment from alcohol and improvement with practice could be attributed to changes in the efficiency of control mechanisms (Rabbitt, 1979a), some of which depend upon the ability to judge response speed accurately. Twenty subjects participated in a four-choice reaction time experiment in which they received no alcohol (NA) in Session 1 and either no alcohol (10 subjects) or 0.8 ml alcohol (A) per kilogram of body weight (10 subjects) in Session 2. The task was to respond as fast and as accurately as possible to each stimulus. In addition, subjects were required to press a fifth key after any response that they considered to be both fast and accurate. Subjects had no difficulty in performing this task: (1) there was a significant difference of 122 msec between the mean response time for correct responses indicated as fast and that for correct responses not indicated as fast, and (2) subjects indicated 1 in 4 correct responses but only 1 in 64 errors. Alcohol increased all response times by approximately 40 msec. In contrast, practice decreased response times less for correct responses not indicated as fast than for correct responses indicated as fast. The ability to distinguish between fast and slow responses was thus unaffected by alcohol, but was improved by practice. Responses indicated as "fast" were significantly faster than errors, and appeared to occur without warning (unlike errors, which tended to end a sequence of increasingly fast correct responses). The results suggest that alcohol and practice influence choice reaction time in qualitatively different ways: Alcohol impairs overall response speed but has no effect on the ability to judge response speed, whereas practice improves both.     

Hypnotic susceptibility and verbal automaticity: automatic and strategic processing differences in the Stroop color-naming task.

The original hypothesis of Dixon, Brunet, and Laurence (1990) that highly hypnotizable (HH) subjects process words more automatically than do low hypnotizable (LH) subjects was retested in a paradigm that separated strategic from automatic processes in the Stroop color-naming task. The words red and blue preceded a color patch that was red or blue. Subjects were told that the word predicted the opposite color 75% of the time. Automatic and strategic processes were assessed by varying the interstimulus interval (ISI) between the word and the color patch. Both HH and LH subjects showed significant strategic effects (faster incongruent-trial, color-naming reaction times than congruent-trial reaction times at ISIs over 400 ms), but only HH subjects showed significant automaticity (significantly faster congruent-trial reaction times than incongruent-trial reaction times at 16.7 ms, the lowest ISI).     

Effects of Contrived information of Female and Male Performance on the Achievement Behavior of Preschool Girls and Boys1

Twenty-four girls and 24 boys enrolled in a university preschool were given two trials each to perform a marble-dropping task. After the first trial, subjects in the sex-appropriate condition were told that children of their sex perform the task better than children of the opposite sex. Subjects in the sex-inappropriate condition were told that children of their sex perform the task less well than children of the opposite sex. It was hypothesized that sex-appropriate subjects would set higher goals for Trial 2 than control subjects receiving no information and that sex-inappropriate subjects would set lower goals than control subjects. The hypotheses were not supported. Instead, children of both sexes set significantly higher goals when told that boys do better at the task. Interpretations of the results are offered.     

Hypothesis-testing strategies: Why two goals are better than one

An intriguing finding in the hypothesis-testing literature concerns a large increase in the proportion of subjects who discover a rule when they are asked to determine two rules rather than that rule alone. This finding is based on Wason's (1960) “2 4 6” task, in which subjects try to discover a rule (ascending numbers) by generating and testing number triples. They are initially given an example (“2, 4, 6”) of the rule that leads to overly specific hypotheses. With single-goal (SG) instructions, subjects try to discover the correct rule and are told whether each triple proposed fits the rule. With dual-goal (DG) instructions, correct and incorrect categories are labelled, respectively, as DAX and MED. Subjects try to discover both rules and are told whether each proposed triple is DAX or MED. Two explanations of why DG subjects do better at rule discovery than SG subjects are tested: the quantity of information and the testing of complementary rules using the prevalent positive-test strategy. Results support the latter explanation: DG subjects outperform SG subjects only if they know the rules are complementary, and that SG subjects' performance does not improve when required to test more triples before announcing their first rule. A third explanation, the positivity of the linguistic label of the feedback, is ruled out. Understanding the superiority of DG instructions might suggest a general method for enhancing rule discovery.     

Changes in repeated references: Collaboration or repetition effects?

According to the Clark & Wilkes-Gibbs' collaborative model of reference, the repetition of a referential communication task produces changes in the making of references (decreasing number of words and of turns with the passing trials, increasing number of definite references and of labels), and these changes are interpreted as revealing the outgrowth of a collaborative process aiming at mutual understanding at the lowest cost. Using a repeated referential paradigm but without any physically present interlocutor, the present study aimed at answering the question of whether these changes are attributable to the mere repetition of the referential task. In adifferent addressee (DA) condition, the subjects were told before each new trial that what they would say would be presented later to another person; in asame addressee 9SA) condition, the subjects were told before each new trial that what they would say would be presented to the same person. With the passing trials, the subjects in the DA condition produced more and more words, but did not use any definite references or labels: These observations have no common point with the ones obtained within a conversational framework. The data obtained from speakers in the SA condition were only slightly different and far from being close to the ones gained in referential dialogues: The number of words remains constant, there was only a slight increase of definite references, and there were no labels. Repetition itself clearly cannot account for the changes in referring that have been reported in recent studies of how subjects cooperate in the making of references.This research was partly supported by a project grant from the National Fund for Scientific Research (Belgium) to Y. Chantraine, research assistant at the University of Louvain in Belgium.     

Empathic joy and the empathy-altruism hypothesis

Three experiments tested whether empathy evokes egoistic motivation to share vicariously in the victim's joy at improvement (the empathic-joy hypothesis) instead of altruistic motivation to increase the victim's welfare (the empathy-altruism hypothesis). In Experiment 1, Ss induced to feel either low or high empathy for a young woman in need were given a chance to help her. Some believed that if they helped they would receive feedback about her improvement; others did not. In Experiments 2 and 3, Ss induced to feel either low or high empathy were given a choice of getting update information about a needy person's condition. Before choosing, they were told the likelihood of the person's condition having improved--and of their experiencing empathic joy--was 20%, was 50%, or was 80%. Results of none of the experiments patterned as predicted by the empathic-joy hypothesis; instead, results of each were consistent with the empathy-altruism hypothesis.     

Encoding of kinesthetic extent information

The difference in codability of kinesthetic extent cues for experimenter-determined vs. subject-determined standards was investigated. The task involved moving a slide along a linear track a distance of one-half the total distance of the track. This distance (the standard) was then reproduced. During the presentation of the standard, reaction time to an auditory probe was recorded. One group of subjects determined their own standard (active condition), while the other group moved the slide to a stop located at the standard distance (constrained condition). All subjects were told that the standard was one-half the total distance. A more active encoding process was hypothesized to occur in the active condition which would be reflected in increased reaction time to the probe. The results did not support the attention hypothesis, in that probe reaction times were not significantly different for the two groups. Rather, the data suggested that the important variable in determining the codability of extent cues was the availability of a strategy and not whether the experimenter or the subject determined the standard.