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.     

The effect of foreperiod duration on reaction time and its relation to interval schedules of reinforcement

Two groups of pigeons were exposed to a simple reaction-time procedure in which mean foreperiod duration was 5, 10, or 20 seconds. For one group, the foreperiods had an arithmetic, or rectangular, distribution; for the second group, they had a constant-probability, or Bernoulli, distribution. Under both distributions, mean response latency was an increasing, negatively accelerated function of mean foreperiod duration. On a given trial, response latency was a function of its associated foreperiod duration: latency was a decreasing function of foreperiod duration in the arithmetic distribution, and an increasing function of foreperiod duration in the constant-probability distribution. Examination of the distribution of latencies revealed a harmonic structure reminiscent of distributions of interresponse times under variable-interval schedules of reinforcement. Taken together, the results confirm and extend previous findings with human subjects, and also suggest numerous similarities to behavior maintained by variable-interval schedules.     

The point of no return in choice reaction time: controlled and ballistic stages of response preparation

A countermanding procedure and race model are used to assess separately the effects of experimental factors before and after the "point of no return" in response preparation. The results reveal details about processes that so closely precede the initiation of movement that they cannot be inhibited. These processes appear to be affected by the repetition of stimulus-response pairs, but not by the physical or semantic properties of the stimuli. A model of response preparation is supported in which response inhibition depends upon the outcome of a race between independent excitatory and inhibitory processes, and reaction time is the sum of the durations of at least two stages, separated by the point of no return.     

The Aubert-Foerster phenomenon and its relation to Manifest Anxiety

Summary The narrowing of the visual field with an increase in distance between a person and a pre-set fixation point was investigated with 20 persons under stable background and with 10 persons under moving background conditions. Optical stimuli were introduced from the periphery and readings were taken at the limit of sharp perception of the figure by the subject. The Aubert-Foerster phenomenon, the easier recognition of small, near objects compared with larger, more distant objects subtending the same visual angle, was used as a starting point. The subjects were equally divided into high and low anxiety groups on the basis of Taylor's Manifest Anxiety Scale.The Aubert-Foerster phenomenon does exist in both experimental situations, under conditions of stable and moving background.Differences in visual angles and in amount of Aubert-Foerster phenomenon are found for the high and low anxiety groups under both experimental conditions.Under conditions of moving background with a centrally imposed task both experimental groups show greater narrowing of the visual angle than they did when exposed to stable background; on the contrary, the visual angle becomes increased when the centrally located task becomes simplified.

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Zusammenfassung Der Winkel zwischen der Blickrichtung und der Sehrichtung, bei welchem ein peripher dargebotener Gegenstand eben erkannt wird, nimmt bei gleichbleibender Größe des Netzhautbildes ab, wenn der Beobachtungsabstand vergrößert wird: Aubert-Foerster-Phänomen.Dieses Phänomen stellt den Ausgangspunkt vorliegender Arbeit dar, in der 30 Versuchspersonen herangezogen wurden, um die Frage nach der Gesichtsfeldeinengung mittels peripher vor unbewegtem und bewegtem Hintergrund einwandernder Figuren zu untersuchen. Die Versuchspersonen in den beiden Versuchsklassen wurden nach Taylors Manifest Anxiety Scale in Gruppen von hohem und niedrigem Anxiety-Wert zusammengefaßt.Das Aubert-Foerster-Phänomen tritt in beiden Versuchssituationen auf, d.h. beim Fixieren der Figuren vor dem bewegten als auch dem unbewegten Hintergrund.Für die hohen und niedrigen Anxiety-Gruppen bestehen in beiden Versuchsklassen Unterschiede hinsichtlich der nach dem Aubert-Foerster-Phänomen zu erwartenden Winkelgröße.Bei den Versuchen vor bewegtem Hintergrund wird der experimentell bestimmte Winkel größer als der theoretisch erwartete, wenn die Anzahl der Reize vermindert, d. h. die Aufgabe vereinfacht wird. Es besteht offenbar eine direkte Beziehung zwischen der geforderten Aufmerksamkeit an der Stelle deutlichsten Sehens und der peripheren Sehleistung.

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Dr. Mangans help in the collection of the data and his advice were greatly appreciated.     

The relation between physical stimulus properties and the effect of foreperiod duration on reaction time

Seven subjects were used in an experiment on the relation between signal modality and the effect of foreperiod duration (EP) on RT. With visual signals the usually reported systematic increase of RT as a function of FP duration (1, 5 and 15 s) was confirmed; with auditory signals no difference was found between FP's of 1 and 5 s while the effect at 15 s was equivalent to that found at 5 s with the visual signal. The results suggest that besides factors such as time uncertainty the FP effect is also largely dependent on the arousing quality of the signal.     

All we need is a cue to remember: the effect of an extinction cue on renewal

In the present study, it was investigated by employing a human fear conditioning paradigm whether an extinction retrieval cue can attenuate renewal of conditioned responding after an extinction treatment procedure, and if so, what the precise role of such an extinction cue comprises. It was hypothesized that such a cue can attenuate renewal and would function as a safety signal capable of directly inhibiting the expectancy of an aversive outcome and conditioned skin conductance responding to a conditioned stimulus. The results demonstrated that the extinguished expectancy of an aversive outcome was renewed when the CS was presented outside the extinction context and that an extinction cue attenuated this effect. This extinction cue, however, only transferred its inhibitory properties to other, non-extinguished stimuli when there was no contextual switch. This safety signal function was not observed after a switch in context. Possible functions of the extinction cue and its application in extinction-based exposure treatments are discussed.     

Short-term effect of physical exercise at lactate threshold on choice reaction time

The duration of the enhancement of choice reaction task efficiency by physical exercise at lactate threshold was studied. After healthy male students completed the exercise or nonexercise (control) period for 10 min., they performed a three-choice reaction task for 20 min. The mean heart rate during the choice reaction task after the exercise was higher than that after the control period (p < .05). For average percentage of correct answers, there were no significant differences between the exercise and control conditions. The reaction time during the first 8 min. of the 20-min. choice reaction task after the exercise period was less than that after the control period and increased gradually thereafter. In conclusion, whereas the choice reaction time was improved by physical exercise at around lactate threshold, the positive effects were seen mainly in the early stages of the task.     

Acute aerobic exercise and information processing: energizing motor processes during a choice reaction time task

The immediate and short-term after effects of a bout of aerobic exercise on young adults’ information processing were investigated. Seventeen participants performed an auditory two-choice reaction time (RT) task before, during, and after 40 min of ergometer cycling. In a separate session, the same sequence of testing was completed while seated on an ergometer without pedalling. Results indicate that exercise (1) improves the speed of reactions by energizing motor outputs; (2) interacts with the arousing effect of a loud auditory signal suggesting a direct link between arousal and activation; (3) gradually reduces RT and peaks between 15 and 20 min; (4) effects on RT disappear very quickly after exercise cessation; and (5) effects on motor processes cannot be explained by increases in body temperature caused by exercise. Taken together, these results support a selective influence of acute aerobic exercise on motor adjustment stage.     

Absorbed in thought: the effect of mind wandering on the processing of relevant and irrelevant events

This study used event-related potentials to explore whether mind wandering (task-unrelated thought, or TUT) emerges through general problems in distraction, deficits of task-relevant processing (the executive-function view), or a general reduction in attention to external events regardless of their relevance (the decoupling hypothesis). Twenty-five participants performed a visual oddball task, in which they were required to differentiate between a rare target stimulus (to measure task-relevant processes), a rare novel stimulus (to measure distractor processing), and a frequent nontarget stimulus. TUT was measured immediately following task performance using a validated retrospective measure. High levels of TUT were associated with a reduction in cortical processing of task-relevant events and distractor stimuli. These data contradict the suggestion that mind wandering is associated with distraction problems or specific deficits in task-relevant processes. Instead, the data are consistent with the decoupling hypothesis: that TUT dampens the processing of sensory information irrespective of that information's task relevance.     

The disruptive effect of an irrelevant message in dichotic listening to word-lists

The results of previous experiments suggest that when listeners are asked to repeat back prose arriving at one ear, their performance is unaffected by the presence (in the other ear) of another independent prose passage in the same voice and of equal intensity. In the present study dichotic messages were employed in which the words were presented quasi-simultaneously and were not connected in meaning. Considerable performance decrement was found from a message on the irrelevant ear even if that message was less intense than that on the relevant ear. Different kinds of error occur, but the principle form of error is a response which is incorrect but nevertheless clearly related to the word presented to the relevant ear. The results extend the findings of Treisman (1967, 1970) who found considerable interference in dichotic listening to pairs of words exactly matched for time of onset; and suggest a general difficulty of selective attention when non-prose material is used.