Operator behavior in a dynamic visual signal detection task

The effects of changes in signal-to-noise ratio (SIN) and feedback state on the operator’s detection behavior, particularly derived operator thresholds, were investigated using a discrete visual signal. It was found that: (1) the operator behaves as if he has established different thresholds as a function of S/N; (2) his decision thresholds are relatively independent of the presence or absence of feedback; and (3) the operator will change his threshold accordingly for a change from one S/N to another. A model of the operator’s behavior, which introduced the concept of “operator” noise. yielded predictions of detection and false alarm probabilities which were extremely close to the observed values.     

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.     

Inter-digital variability in the palmer sweat indices of adult stutterers

This study examined the relationship of mean palmar sweat density of all fingers of each hand, thumbs excluded, to asymetrical interdigital sweat variability in adult stutterers. In addition, the relationship of mean print density to part word repetitions and prolongations was investigated.

A modification of the palmar sweat printer developed by Brutten (1957) enabling the accommodation of eight fingers, was employed to obtain simultaneous PSI under identical controlled conditions for all fingers.

Results indicated that the eight fingers are not reliable areas for the determination of palmar sweating in adult stutterers. Consequently, the PSI as it is currently employed, as well as the method used in the present study, does not appear to be an acceptable objective measure of ANS arousal in adult stutterers.