Metacontrast and brightness discrimination

An attempt was made to obtain U-shaped masking functions in two metacontrast experiments. Trained Ss judged whether a square test stimulus (TS) was bright or dim. The TS was presented alone or in conjunction with an adjacent pair of square masking stimuli (MS) whose energy equaled the bright TS. The stimulus onset asynchronies (SOA) rangedfrom 0 to 125 msec. The task minimized the role of apparent movement cues as a reliable basis for judgrnent. Similar studies have employed TS plus MS vs MS alone as the alternatives, allowing apparent movement to be a cue. Brightness accuracy was a U-shaped function of SOA. This finding is consistent with neural-net models (Weisstein, 1968). However, analysis of Ss’ response bias suggested an alternative explanation involving the MS as a comparison stimulus at short SOA. It was concluded that U-shaped masking functions are also consistent with theories based upon independent component processes, e.g., Schurman and Eriksen (1970) and Uttal (1970).     

Salience of stimulus and response features in choice-reaction tasks.

A pattern of differential reaction time (RT) benefits obtained in spatial-precuing tasks has been attributed to translation processes that operate on mental codes formed to represent the stimulus and response sets. According to the salient-features coding principle, the codes are based on the salient stimulus and response features, with RTs being fastest when the two sets of features correspond. Three experiments are reported in which the stimulus and response sets were manipulated using Gestalt grouping principles. In the first two experiments, stimuli and responses were grouped according to spatial proximity, whereas in the last experiment, they were grouped according to similarity. With both types of manipulations, the grouping of the stimulus set systematically affected the pattern of precuing benefits. Thus, in these experiments, the organization of the stimulus set was the primary determinant of the features selected for coding the stimulus and response sets in the translation process.     

Same-different judgments of multiletter strings: insensitivity to positional bias and spacing

Several recent studies of multiletter matching have included pairs of strings that have the same letters in different positions (rearranged pairs). The task can be defined such that these rearranged pairs are correctly classified as different (i.e., subjects respond "same" only if the strings have the same letters in the same positions--the order task) or as same (i.e., subjects respond "same" if the strings have the same letters regardless of their positions--the item task). The order task produces left-to-right serial-position effects, whereas the item task produces U-shaped serial-position effects. Because these differences suggest that subjects may be able to exert strategic control over the comparison process, two sets of experiments were designed to test whether or not subjects can change the relative weightings devoted to the respective serial positions. In Experiments 1 and 2, the probability that a mismatch occurred in the different positions was manipulated. In Experiments 3 and 4, the physical spacing between letters, as well as whether or not the spaces were filled with neutral noise characters, was varied. None of the manipulations had much influence on the serial-position effects. Thus, the distinct serial-position effects for the order and item tasks apparently are mandatory and not due to any voluntary comparison strategy.     

Patterns of regional cerebral blood flow during attempted reading aloud by stutterers both on and off haloperidol medication: Evidence for inadequate left frontal activation during stuttering

Two stutterers, both recent college graduates, were subjected to regional cerebral blood flow measurements while attempting to read aloud. Each one received two measurements, one of which was under the influence of haloperidol, 3 mg daily. Both subjects showed improvement on medication, allowing a stuttering versus essentially no stuttering comparisons for each subject. Both subjects showed higher Broca's area flow in the right compared to the left hemisphere, during stuttering. Both showed higher Wernicke's area flow in the left compared to the right hemisphere, however, during stuttering. During reading aloud without stuttering, however, the Brocas's area flows were reversed, now showing a left hemisphere advantage. The results were interpreted as consistent with H. M. Sussman and P. F. MacNeilage's (1975, Neuropsychologia, 13, 19–26) proposal that stutterers exhibit conventional left cerebral dominance for speech reception, but inadequate left cerebral dominance for speech production.     

The influence of irrelevant location information on performance: A review of the Simon and spatial Stroop effects

The purpose of this paper is to investigate the effect of irrelevant location information on performance of visual choice-reaction tasks. We review empirical findings and theoretical explanations from two domains, those of the Simon effect and the spatial Stroop effect, in which stimulus location has been shown to affect reaction time when irrelevant to the task. We then integrate the findings and explanations from the two domains to clarify how and why stimulus location influences performance even when it is uninformative to the correct response. Factors that influence the processing of irrelevant location information include response modality, relative timing with respect to the relevant information, spatial coding, and allocation of attention. The most promising accounts are offered by models in which response selection is a function of (1) strength of association of the irrelevant stimulus information with the response and (2) temporal overlap of the resulting response activation with that produced by the relevant stimulus information.     

An empirical evaluation of the SYNWORK1 multiple-task work environment

SYNWORK1 is a multiple-task work environment that allows up to four tasks (memory search, arithmetic, visual monitoring, and auditory monitoring) to be performed concurrently. Experiments were conducted to evaluate performance and subjective workload for each individual task and all combinations of tasks at two presentation rates. At the slower default rates, the three experiment-paced tasks were not very demanding, and improvements with practice were due primarily to the subject-paced arithmetic task. Doubling the presentation rates made the demands of all tasks more comparable and decreased the influence of arithmetic performance. SYNWORK1 is useful for comparisons between populations of individuals and evaluations of arousal-related variables, and, with modification, could provide a tool for assessing basic issues in multiple-task performance.     

The concept of configuration of interpersonal relations in a group as a time-dependent stochastic process

To explain changes in the sociometric configuration of a group through time, a problem arises of the extent to which such changes may be viewed as the aggregation of part-processes occurring at the level of two-person choice structures. A possible model is a Markov chain in which three possible states are mutual choice, one-way choice, and indifference, one realization for each pair of choosing individuals in the group. Choice data for an eighth-grade classroom are fitted to this model and are used to answer questions of constancy of transition probabilities, order of the chain, and sex differences.     

Mental Health Clinicians' Beliefs About the Biological, Psychological, and Environmental Bases of Mental Disorders

The current experiments examine mental health clinicians' beliefs about biological, psychological, and environmental bases of the DSM-IV-TR mental disorders and the consequences of those causal beliefs for judging treatment effectiveness. Study 1 found a large negative correlation between clinicians' beliefs about biological bases and environmental/psychological bases, suggesting that clinicians conceptualize mental disorders along a single continuum spanning from highly biological disorders (e.g., autistic disorder) to highly nonbiological disorders (e.g., adjustment disorders). Study 2 replicated this finding by having clinicians list what they thought were the specific causes of nine familiar mental disorders and rate their bio–psycho–environmental bases. Study 3 further found that clinicians believe medication to be more effective for biologically based mental disorders and psychotherapy to be more effective for psychosocially based mental disorders. These results demonstrate that even expert mental health clinicians make strong distinctions between psychological and biological phenomena.     

Transfer of learning in choice reactions: contributions of specific and general components of manual responses

Manifestations of learned skills and knowledge are known to be context-dependent. However, a study of perceptual-motor learning [Tagliabue, M., Zorzi, M., & Umiltà, C. (2002). Cross-modal re-mapping influences the Simon effect. Memory and Cognition, 30, 18-23] reported context-independent transfer of a learned stimulus-response (S-R) mapping to a task in which the mapping is no longer relevant. Although similar results were observed in subsequent studies, these studies also provided an indication that the transfer is context-dependent. The present study investigated the issue of context-dependence of the transfer of a learned S-R mapping. In experiment 1, groups of participants performed choice-reaction tasks with either the same or different response modes (keypresses or joystick movements) in the practice and transfer sessions. Smaller transfer effects were observed for those who switched response mode in the transfer session than for those who did not, indicating that transfer of the learned mapping is context-dependent. However, transfer also occurred for the former group, indicating that the transfer effect is dependent on both general and specific response components. In experiment 2, the same task conditions were examined, but with action effects consistent across the practice and transfer sessions, which were assumed to introduce a contextual feature that was common to the two sessions. The influence of action effects on transfer depended on the practiced response. The results are discussed in terms of feature overlap between the learning and test contexts, and an association network model of learning and response selection.