Focal changes in cerebral blood flow produced by monetary incentive during a mental mathematics task in normal and depressed subjects

The purpose of this experiment was to determine the effect of incentive-induced arousal on the diffuse and regional cerebral blood flow (rCBF) response during cognitive activation for normal and depressed groups. Two normal rest CBF measurements were followed by two mental mathematics activation CBF measurements. For the first activation measurement, half the subjects in each group were offered monetary incentive for correct performance and half the subjects received no monetary incentive. All subjects were offered monetary incentive on the final activation run. The effect of monetary incentive on the first activation run was to increase CBF activation at four detectors in the left hemisphere. Incentive did not affect the CBF activation response when introduced following practice on the activation task (on the final run). Depressed groups had lower resting blood flow than normals, but the distribution of flow and the CBF response to incentive were almost identical in the two groups.     

Response input interface

A circuit for interfacing experimental response signals with logic apparatus that controls experimental events is described. The unit shapes and holds the signal until its presence has been detected by the controlling program.     

Typicality and familiarity of faces

We examined context-free familiarity information as a source of the effects of face typicality upon face recognition. Experiment 1 tested memory for typical and unusual faces by (1) subjects who received an input list followed immediately by a recognition test (standard condition), (2) subjects who viewed all test faces (targets and lures) prior to the input list (prefamiliarization condition), and (3) subjects who viewed all test faces after the input list but prior to recognition (postfamiliarization condition). Although false-alarm errors in the standard condition were lower for unusual than for typical faces, this effect was reduced by postfamiliarization and was eliminated entirely by prefamiliarization. The prefamiliarization and typicality effects were replicated in Experiment 2, which showed that patterns of old judgments were compatible with the hypothesis that, although familiarity of new faces is greater if these faces are typical, the increment in familiarity that results from presentation is greater if these faces are unusual.     

Response bias in very first judgments of the reflectance of grays: Numerical versus linear estimates

Three hundred unsophisticated Os judged the lightness of a gray, reflectance 44%, against a white, reflectance 83%. Half gave a numerical estimate calling the white 100. The remainder marked a 100 mm line labeled 100 at one end and zero at the other. Both distributions of estimates were skewed with a mode around 60. The linear estimates tended to avoid the middle of the line (p<.01).The numerical estimates tended to end in zero or five (p<.001). The two distributions were not quite reliably different, but the medians of subgroups of 10 Os drawn from the two distributions were reliably different (p<.05).