The bias of an estimate of coupled slack in stochastic PERT networks

An earlier paper presented a method for using response times to construct a PERT network representing the mental activities in a task. A key role in this method is played by parameters called coupled slacks. The magnitudes of the coupled slacks are used to test the validity of a PERT model and to deduce aspects of the structure of the network. In a stochastic PERT network, the usual estimate of coupled slack based on the mean completion times can be biased. Distribution-free upper and lower bounds are derived for the bias, and it is shown that the bias approaches zero as the probability of relatively long prolongations increases. It is also shown that the expected value of the estimate of coupled slack between two activities is negative only if the two activities are in a Wheatstone bridge. Finally, an estimate of the increase in completion time due to prolonging an activity, given that the prolongation did in fact increase the completion time, is derived.     

When a bystander becomes an accomplice: Situational determinants of reactions to dishonesty

In a series of experiments, undergraduates (N = 288) performed a task with a confederate who subsequently lied about his or her performance in order to obtain a cash bonus. The probability of bystanders' reporting the dishonesty and refusing to sign a document attesting to the confederate's score was differentially affected by situational factors and sex of the bystander, wrongdoer, and authority figure. Bystanders were most apt to report the misdeed when they were competing against rather than working either independently or cooperatively with the culprit, at least when the bonus was provided by a large corporation. In addition, females were more likely than males to report when the victim was another person rather than either a corporation or the bystander himself, and both sexes were more apt to report a female wrongdoer than a male one. Persons who initially reported the misdeed were less likely to become active accomplices than were those who failed to report it. Furthermore, less written verification of the falsehood occurred when (a) nonreporters were performing independently rather than either competing against or working cooperatively with the culprit for the bonus, and (b) a male was in an immediate position of authority.     

When “I like you” indicates disagreement an experimental differentiation of information and affect

It was hypothesized that the independent manipulation of the informational content and the affective meaning of personal evaluations would indicate that both informational judgments and attraction responses are a joint function of the two stimulus components. In a 2 × 2 factorial design, each of 80 subjects was exposed to a videotape message from a stranger which was either affectively positive or negative and informationally positive or negative. Analysis of variance indicated that perceived similarity was influenced only by the informational variable (p < .0001) while attraction was influenced by both information (p < .0001) and affect (p < .002). It was suggested that the most inclusive theories of person perception and attraction will necessarily encompass elements of both cognitive and reinforcement formulations.     

Effect of shifts in body weight on rats' straight alley performance as a function of reward magnitude

The performance of rats trained in a straight alley for 55 trials under 75% body weight and then shifted to 90% body weight was compared to that of rats trained only under 90% body weight. When training was with a small reward the speed of the shifted group decreased to the level of the 90% small reward control groups, but when training was with a large reward the speed of the shifted group dropped below the level of the 90% large reward control group. Thus, the effects on performance of shifting deprivation level following extended training depend on the reward magnitude employed.     

Partial reward training level and reward magnitude: Effects on acquisition and extinction

Two groups of 10 rats each received either a large magnitude (0.90 g) or a small magnitude (0.18 g) of partial reward (PR) and seven successive acquisition-extinction sessions in the runway. The large magnitude PR group ran much faster than the small magnitude PR group in the early acquisition sessions with differences between the groups declining over sessions. In the early extinction sessions, the large magnitude PR group showed greater resistance to extinction than the small magnitude PR group, but in the late extinction sessions this relation reversed itself. Finally, resistance to extinction decreased over sessions, this decrease being greater under a large than under a small magnitude of PR.     

Shock preexposure and the reduced effectiveness of shock

In three experiments experience with shock was shown to reduce the effectiveness of shock as a reinforcer or motivator. In Experiment 1 rats were given signaled shock in a box separate from the runway where they were subsequently punished. These rats were less suppressed by shock punishment than rats that had no previous shock experience. In Experiment 2 preshocked rats were less suppressed by punishment and were slower to learn an escape-avoidance response than nonpreshocked rats, whether the preshock was signaled or unsignaled. In Experiment 3 as number of CS-shock pairings increased, fear of the CS decreased as did fear of the context. These results suggest that some central adaptation process produced by experience with shock reduces the effectiveness of shock as a reinforcer whenever shock is used repeatedly. This is independent of other effects, such as context blocking, that can affect responding after shock preexposure.     

Attributing causes for one's own performance: The effects of sex,norms, and outcome

Two experiments were conducted to determine the effect of sex of subject, stated sex linkage of task, and task outcome on causal attributions of an actor's performance. Results from both studies showed that: (1) males evaluate their performance more favorably than do females, despite equivalent objective scores; (2) males claim greater ability than do females following task performance; and (3) females are more prone to use luck to explain performance. The evidence also suggests that the difference between males and females in performance evaluation and self-attribution occurs most strongly in response to failure and on masculine tasks. The results are interpreted in terms of a general expectancy model.     

Percentage body weight and the successive negative contrast effect in rats

In two runway experiments employing rats the successive negative contrast effect was evaluated for animals maintained at high or low body weights. In both experiments the effects on performance of shifting reward magnitude were independent of body weight. These results contrast with those of previous studies in which the successive negative contrast effect occurred only under low body weight. It was suggested that when conditions are maximal or near maximal for production of the successive negative contrast effect, as they were here but not in previous investigations, body weight will not influence the size of this effect.     

Case study of a Thai conduction aphasic

A case study of a 55-year-old nonfamilial left-handed monolingual Thai patient with clinical and pathoanatomic evidence of major infarction in the left temporoparietal region is presented. He was studied at 9 years poststroke with a Thai adaptation of the Boston Diagnostic Aphasia Exam and supplementary tests. His language characteristics included fluent spontaneous speech, near-normal auditory language comprehension, and poor repetition, leading to a diagnosis of conduction aphasia. In regard to this aphasic syndrome, issues concerning classification, neuroanatomic correlates, and underlying neuropsychological mechanisms are addressed. The nature of his grammatical disturbance is examined critically in light of the notion of “information load.”     

Threatened retaliation from the victim as an inhibitor of physical aggression

Sixty male undergraduates participated in an experiment designed to investigate the effects of apparent probability of retaliation from the victim and level of prior anger arousal upon adult aggressive behavior. It was hypothesized that threatened retaliation would be highly effective in inhibiting subsequent aggression under conditions where subjects had not previously been angered by the victim, but would generally fail to inhibit such behavior under conditions where they had previously suffered strong provocation at the hands of this person. Support was obtained for both of these predictions. Findings were discussed in terms of their implications for the prevention and control of human violence in naturalistic social situations.     

Confrontation naming impairment in dementia

In tone languages pitch variations (tones) serve to distinguish the lexical meanings of words. This study was conducted to examine the extent and nature of impairment in the perception of tones by aphasic patients who were monolingual speakers of Thai, a tone language which has five contrastive tones (mid, low, falling, high, rising). Six subjects participated in the study: two Broca aphasics, one transcortical motor aphasic, one conduction aphasic, one right brain-damaged nonaphasic, and one normal control. Three sets of stimuli (two real-speech, one synthetic-speech) were presented for identification, each set containing five Thai words minimally distinguished by tone. Results of the perception tests indicated that the performance of all four left brain-damaged aphasics differed significantly from that of the normal control, while the performance of the right brain-damaged nonaphasic did not. The normal performance of the right brain-damaged nonaphasic patient on this tone identification task suggests that deficits in the perception of tone exhibited by left brain-damaged patients can be attributed specifically to pathology in the language dominant hemisphere rather than to a general brain-damage effect. No difference in performance among the left brain-damaged patients could be attributed to a specific type of aphasic syndrome. The pattern of tonal confusions of the aphasics in comparison to that of normals suggests that their deficit is primarily quantitative rather than qualitative. Although two (mid, low) of the five tones accounted for a large percentage of the aphasics' errors, no uniform rank order of tones in terms of identifiability could be established across aphasic subjects, which suggests that their deficit is general to all five tones rather than selective to individual tones.     

Attributions and other inferences: Processing information about the self versus others

This study focuses on the attributional inferences involved in the comprehension of behaviors and on possible differences between the process of comprehending one's own behaviors and those of another person. Both the content of attributional judgments and the time taken to make the judgments were measured, in a design involving the comprehension of behaviors that were high or low in desirability and distinctiveness and that were understood as the subject's own versus another person's. Results show that the inferential processes in the comprehension of one's own and another's behavior are generally similar. Exceptions are where organized knowledge about the self (a self-schema) is brought into use and where differences in “perspective” between self and other influence processing. Discussion centers on the implications of the results for theories of comprehension and inference, including extensions needed to handle the self/other distinction.     

Channels and stages in human information processing: A limited analysis of theory and methodology

This article reviews the status of the theoretical construct of capacity. Four basic questions are discussed: (1) What is capacity? (2) How is capacity measured? (3) Is capacity limited? (4) If so, where is it limited? It is claimed that empirical answers to these questions have been unsatisfactory due to theoretical and methodological issues that need be resolved. Data are presented to illustrate such difficulties. The construct of capacity has become more and more vacuous and caution is required whenever capacity is invoked to explain behavior. These problems can be overcome by careful research and well-defined models. Capacity can be a soup stone, a millstone, or a touchstone, depending upon how it is used.     

Voice onset time in aphasia: Thai. I. Perception

This study investigated left brain-damaged aphasic and right brain-damaged non-aphasic patients' ability to label synthetic speech continua differing in voice onset time (VOT) at three places of articulation. The language chosen for investigation was Thai, which exhibits 3 contrasting labial and apical stop categories (voiced, voiceless unaspirated, voiceless aspirated) and 2 contrasting velar stop categories (voiceless unaspirated, voiceless aspirated). Results of the labelling task indicated an impairment in VOT perception at all three places of articulation across clinical types of aphasia. Normal performance by the right brain-damaged patient indicated that deficits in VOT perception can be attributed to pathology specific to the language-dominant hemisphere. No relation was found between the aphasic patient's level of auditory language comprehension and his performance on the VOT perception task. It is suggested that the aphasics' impairment reflects a deficit in phonological processing at the linguistic level.     

Reward schedule effects in extinction: Intertrial interval, memory, and memory retrieval

Rats were trained in a runway such that partial reward occurred on Trial 1 of the day and consistent reward on subsequent massed trials (Group PRT1), or consistent reward occurred on Trial 1 of the day and partial reward on subsequent massed trials (Group PRTM). Under spaced (24-hr) extinction, Group PRT1 was more resistant to extinction than Group PRTM and under massed (1-min) extinction, Group PRTM was more resistant to extinction than Group PRT1. These findings suggest that (a) distinctive stimuli are associated with Trial 1 of the day and with subsequent massed trials, (b) these distinctive stimuli function as retrieval cues for memories, memory retrieval being independent of intertrial interval, and (c) behavior in extinction is controlled by a stimulus compound consisting of the memory of nonreward plus stimuli which accompany the memory of nonreward on rewarded acquisition trials.     

Some theory and results for metrics for bounded response scales

In an earlier note, a new metric for bounded response scales (MBR) was introduced which resembles the city-block metric but is bounded above. It was suggested the MBR may be more appropriate than minkowski metrics for data obtained with bounded response scales. In this article, some formal properties of the MBR are investigated and it is shown that it is indeed a metric. Empirical predictions are then derived from the MBR and contrasted with those of a “monotonicity hypothesis,” which holds that dissimilarity judgements tend to be biased towards overestimation of larger distances, and with the predictions of the minkowski metrics, which imply additivity of collinear segments. Some empirical results are presented which contradict the monotonicity hypothesis and the minkowski metrics, and favor the MBR. Finally, the logic used to motivate the MBR is invoked to define a subadditive concatenation for bounded norms in the one-dimensional case, which may be useful in psychophysical work where the upper bounds are often real, rather than due to the response scale. This concatenation predicts understimation for doubling and overestimation for halving and middling tasks.     

The role of inference in children's comprehension and memory for sentences

In a series of studies, young children often failed to construct and remember inferred relationships which they were capable of understanding. A cued recall procedure was employed to assess the relative effectiveness of implicit and explicit word prompts for sentence memory. The implicit cues were much less effective than the explicit cues for 6–7 yr old children while the cue types did not differ for 11–12 yr olds. Instructions to imitate the actions described by the sentences eliminated the memory difference for the young children. Developmental improvement in spontaneous inferential operations and intentional plans to remember are mechanisms which appear to yield an elaborated memory representation and greater access routes through indirect and implied relationships.     

Deprivation and reward stimuli as compound stimuli

In Experiment 1 the experimental group was tested with a deprivation level and a reward magnitude which it had experienced previously but which it had not experienced in combination. This group was inferior in test performance to a group which had experienced the test deprivation-reward combination prior to test. These results were interpreted as indicating that deprivation stimuli and reward stimuli form a compound stimulus and training on the elements of the compound produces performance inferior to training directly on the compound. In Experiment 2, the decrement associated with two different shifts in deprivation and reward did not differ despite the different size change of total incentive involved in the two shifts. The results were interpreted as indicating that the deprivation-reward stimulus is not produced by a single underlying incentive mechanism.