Human subjects were tested in a free-operant avoidance procedure. Shock could be avoided by the emission of a verbal response of adequate intensity and duration. These schedules were found to control the emission of verbal operants in the same way they control motor operants. Some subjects showed conventional control by this schedule with or without response-produced feedback. Other subjects verbalized at a high rate under both these conditions until the addition of response cost brought this behavior under conventional schedule control.
Relationship between the electroencephalogram, eye-movements and fluctuations of visual perceptionEEG activity and eye movements were recorded while 5s inspected a Ganzfeld or diffuse dark figures introduced into a Ganzfeld. Reports of deterioration of visual perception under all stimulus conditions were preceded by a period of reduced eye movement, but were not associated with a return of EEG alpha activity.Observers report an experience of blank-out or loss of visual perception after a period of exposure to a uniformly illuminated homogeneous field or Ganzfeld (Cohen, 1957). Moreover, areas of inhomogeneous hue or brightness on an otherwise structureless field seem to fade into the background after a time (Guilford, 1927;Cohen, 1958). A similar adaptational mechanism probably underlies both these effects and the fade-out of stabilized retinal images, but evidence from their physiological correlates is unclear. Cohen & Cadwallader (1958) reported that susceptibility to Ganzfeld blank-out was positively correlated with the level of alpha activity in Ss' resting EEG. Tepas (1962), however, found that blank-out periods were little related to alpha activity but were strongly associated with periods of reduced eye-movement. This parallels Guilford's (1927) observation that unstabilized images fade when there is little eye movement, but there are no data to hand on the EEG correlates of this effect. Lehmann et al (1957) reported that the fading of stabilized retinal images is associated with the return of EEG alpha trains in some Ss.The present study investigates the Ganzfeld blankout effect and the fade-out of unstabilized images by simultaneously monitoring both occipital EEG potentials and eye movements using two groups of Ss differentiated on the basis of their levels of resting alpha activity.
SubjectsSix young male Ss having no known visual or neurological defect were used. Four Ss showed frequent alpha trains when resting. Two Ss gave fast, low amplitude EEG traces even when resting with eyes closed.
ApparatusEEG, electrooculograph potentials, subject responses and time marks were recorded on a Beckman RB dynograph. EEG electrodes were attached with Bentonite at the 10-20 position ipsilateral to the stimulated eye. Eye movement was monitored via 3 mmdisc electrodes placed at the inner and outer canthi of the stimulated
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