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Biomedical subjects

R W Proctor

Publications and source records attributed to R W Proctor.

At least 55 records · Page 3Linked to original sources
PubMed1985

Order-relevant and order-irrelevant decision rules in multiletter matching.

Two experiments examined order effects in multiletter matching. In each experiment, subjects used one of two decision rules that differed in whether pairs of letter strings that contained the same letters, but in different orders (rearranged pairs), were classified as same or different. Method of presentation also was varied, with the two strings in each pair being presented either simultaneously or successively in one experiment, and with the exposure duration of the second of two successively presented strings being either short or long in the other. Latency and accuracy of responding to the rearranged pairs varied as a function of the amount of positional displacement, with the two tasks showing similar, but mirror image, patterns. This outcome suggests that most of the order effects are attributable to processes common to both tasks, although there was some evidence for a contribution from task-specific processes as well. Both method-of-presentation manipulations had little influence on the order effects, suggesting that the effects are attributable to perceptual and decision processes, rather than to memory processes. The results are most consistent with a model that assumes position-sensitive comparisons, with the same-different decision based on pooled information.

Decision Making↗
PubMed1984

On the advance preparation of discrete finger responses.

Most studies that examined the precuing of motor responses have been interpreted as indicating that response specification is a variable-order process. An apparent exception to this conclusion was obtained by Miller (1982) for the preparation of discrete finger responses. Precuing was beneficial only when the precued responses were on the same hand, suggesting that response specification occurs in a fixed order, with hand specified before other aspects of the response. Three experiments examined this discrepant finding for discrete finger responses. Experiment 1 demonstrated that with sufficient time (3 s), all combinations of responses can be equally well prepared. Experiments 2 and 3 showed that the precuing advantage for same-hand responses at shorter precuing intervals is due to strategic and decision factors, not to an ability to prepare these responses more efficiently. Preparation of finger responses, thus, also appears to be variable. This conclusion poses problems for Miller's extension of the precuing procedure to the evaluation of discrete versus continuous models of information processing.

Cues↗
PubMed1983

The influence of metacontrast masking on detection and spatial-choice judgments: an apparent distinction between automatic and attentive response mechanisms.

Several studies of metacontrast masking in the 1960s apparently showed that the latency of simple detection responses was uninfluenced by the phenomenal dimming of the target induced by the mask. More recent studies using more suitable methodologies have clearly shown that such is not the case for situations in which the masking is a monotonically decreasing function of stimulus onset asynchrony. Experiment 1 investigated this issue for the situation in which masking is a U-shaped function of stimulus onset asynchrony. Contrary to the results obtained in monotonic masking situations, simple detection responses were not slowed by the masking. Experiment 2 demonstrated that although detection responses are not slowed in the U-shaped masking situation, spatial-choice judgments are. Experiments 3 and 4 indicated that this masking effect on spatial-choice reaction time is lost relatively rapidly with practice. However, changing the stimulus-response assignments reinstates the effect. The experiments suggest that for the situation in which U-shaped masking functions are obtained, responses that require attention (spatial-choice judgments early in practice or after stimulus-response relationships have been switched) are influenced by the metacontrast-induced phenomenal dimming, whereas responses that are automatic (i.e., detection responses; practiced spatial-choice judgments with consistent stimulus-response mappings) are not.

Adolescent↗
PubMed1983

Recognition memory for pictures as a function of poststimulus interval: an empirical clarification of existing literature.

Shaffer and Shiffrin (1972) found no effect of the duration of a blank poststimulus interval on recognition memory for visual scenes. The majority of subsequent studies, however, have found a positive relationship between interval duration and recognition accuracy. The present experiments were conducted to clarify these contradictory outcomes. Experiment 1 determined that Shaffer and Shiffrin's results are replicable with the method that they used in which stimulus durations and poststimulus-interval durations vary randomly within the study list. Experiments 2-3 showed that this random intermixing of durations is the critical factor that results in poststimulus interval having no effect. The results were interpreted in terms of a voluntary rehearsal process that is abandoned when there is uncertainty regarding the time of onset and offset of the stimuli.

Discrimination Learning↗
PubMed1983

An empirical note on the role of verbal labels in motor short-term memory tasks.

Previous studies of motor short-term memory have shown that when a criterion movement on a semicircular positioning task is accompanied by an appropriate verbal label (a clock-face position), recall of the movement is more accurate than when only the movement is presented. This increased accuracy could be due to either the additional spatial information provided by the label or enhanced retention of the movement information. These two alternatives cannot be distinguished on the basis of previous studies because the studies have not evaluated movement accuracy following presentation of the label alone. The present study employed such a condition in addition to the movement-only and movement-plus-label conditions to distinguish between the two hypotheses. In all conditions, subjects were asked to move to the criterion position after a retention interval of either 5 sec or 60 sec. Evidence indicated that subjects who received both the label and the movement tended to use the spatial information provided by the label at the 60-sec interval. The evidence did not indicate that the verbal label actually enhanced retention of the movement information.

Journal Article↗
PubMed1979

Secondary task modality, expectancy, and the measurement of attentional capacity.

Previous studies have obtained conflicting evidence regarding the effect of probe modality when a secondary probe task is used to measure attentional demands of a primary letter-matching task. The present experiments found no difference in the shape of the probe reaction time functions for auditory and visual probes as long as probe modality was known. When probes "unexpectedly" occurred in the modality that was different from the majority of the probes, differences were obtained. Only the unexpected auditory function changed, shape relative to the others, with reaction time to probes that occurred early in the matching task sequence being increased. The results are interpreted as supporting a role of attentional capacity in the activation of structures that accept relevant sensory input.

Attention↗
PubMed1977

Time, capacity, and selection between perceptual attributes.

Three experiments were run to determine whether time and central-processing capacity are requried to select between perceptual attributes. A same-different matching task was employed for all experiments. In Experiments 1 and 2, three sets of stimulus pairs were used, each of which varied along only one relevant perceptual dimension (color, size, or form). In Experiment 1, reaction time on the matching task was shown to be faster when the stimuli were presented in blocks in which all stimulus pairs came from the same set (blocked presentation) than when stimulus pairs from each of the three sets were randomly intermixed (random presentation). In Experiment 2, reaction time on a secondary probe task was faster during the encoding stage of a sequential mathcing task with blocked presentation than with random presentation. Experiment 3 indicated that this outcome could not be attributed to a difference in the number of possible stimulus alternatives. Thus, the results support the hypothesis that time and central-processing capacity are required to select between perceptual attributes.

Acoustic Stimulation↗