Perception of sequentially presented tactile point stimuli

Either two or three brief (10 msec) airjet stimuli were sequentially presented to any of the 24 interjoint regions of the fingers (thumbs excluded). The stimulus onset interval (SOI) ranged from zero (simultaneous presentation) through 200 msec. The S’s task in one part of the experiment was to report the positions stimulated in the order that the stimuli were presented; in a second part it was to rate the apparent motion produced by the stimulus sequence. While the ability of Ss to spatially localize the stimuli was a constant independent of SOI, their ability to temporally order the stimuli depended strongly on SOI. With two stimuli, these sequential errors decayed exponentially with SOI with a time constant of 26 msec. With three stimuli, however, both the sequential errors and equivalent temporal Urnen were more than twice as large as with two stimuli, indicating that the three-stimulus task is considerably more difficult than the two, and that the same simple temporal resolution model does not explain both cases. A model with a constant rate of information uptake, however, can explain both of these cases.     

The Declining course of recognition memory

Recognition memory for words can decline, sometimes precipitously, over the course of the recognition test. Decrements of as much as 75% in d’ have been observed from the first quarter of testing to the last. and decrements of 40%–50% are not uncommon. Proactive mechanisms, imperfectly understood, appear to underlie such declines: Processing early input renders late input less recognizable, and making early recognition judgments renders later judgments more difficult. At the same time, the processing of late-input words fails to inhibit the recognition of the words that preceded them.     

An inexpensive circuit for beta,alpha, theta,or delta EEG biofeedback

An inexpensive circuit is described for EEG biofeedback or measurement. The circuit is designed to interface easily with most basic EEG machines. It taps the output from a single recording channel of the basic EEG instrument and provides the following for each EEG band (beta, alpha, theta, and delta): (a) very selective bandpass discrimination, (b) variable center frequency, (c) variable threshold at which feedback will be provided, or the measurement made, and (d) use with any biofeedback stimulus or measurement device that one wishes to switch contingent with S’s EEG rhythms.     

Children's interpretation of adult nonreaction: A trial-by-trial self-report assessment and evidence for contrast effects in an observational context

The study investigated children's interpretation of blank reaction (nonreaction) from one adult to another as a function of its pairing with positive or negative overt feedback. Each child watched through a one-way mirror as an evaluating adult provided feedback to a second adult who was performing on a two-choice discrimination task. After six initial blank reaction trials, children observed one of four types of feedback combinations over 60 experimental trials: (a) right feedback on some trials and blank reactions on others, (b) wrong feedback on some trials and blank reactions on others, (c) right, wrong, and nonreaction on different trials, or (d) nonreaction on all trials. There was little evidence that children consistently interpreted blank reaction as meaning right independent of feedback combination. In contrast, in the Right-Blank and Wrong-Blank feedback combinations, children interpreted blank as meaning the opposite of the overt feedback it was paired with on over two-thirds of the trials, with no sex differences or test anxiety effects.