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The magnitude of task-evoked pupillary dilations during mental activity has previously been shown to index the cognitive capacity utilized in the performance of the mental task. To determine the relation between "intelligence" and capacity demands during mental activity, task-evoked pupillary dilations were measured while two groups of university students(More)
Through the use of a quantitative extension of signal detection theory, the brain events associated with the detection and recognition of weak acoustic signals were examined by recording brain event-related potentials. The early N100 componenet of the event-related potential varied only with detection, whereas the late P300 component varied with both(More)
Three studies are described in which the task-evoked pupillary response is recorded during simple and disjunctive reactions in order to examine its contribution as a measure of the motoric and cognitive aspects of performance in these tasks. In simple reactions a pupillary dilation began about 1.5 sec before the imperative stimulus and peaked about 1 sec(More)
Magnetic fields produced by a dipolar source implanted in a spherical conductor and a human cranial specimen were measured in the magnetoencephalogram (MEG). The location of the source was accurately computed in the spherical conductor from the identified magnetic field extrema using equations for a current dipole in a sphere. This same method was(More)
Local paroxysmal discharges of epileptic tissue within the human brain, which may be electrically recorded as voltage spikes in the electroencephalogram, also generate extracranial magnetic fields. These fields were assessed by means of recently developed neuromagnetometric techniques. Surface measurements of magnetic spike field strength in the region of(More)
The idea that hierarchically higher brain processes require greater amounts of central nervous system vigilance or activation for their execution was tested in two experiments measuring pupillary dilation during the decision interval of a hierarchically structured letter-matching task. Larger dilations indicative of increased activation were observed for(More)
Lateralized functional specialization of cortical processing of linguistic and spatial information and anatomical lateralization of processing of hemiretinal stimuli were investigated with a randomized factorial design in 14 right-handed male undergraduates using EEG alpha-contingent visual stimulation. Words or geometric designs of equal luminosity and(More)