Effects on the event-related potential (ERP) waveform of differences in stimuli (task difficulty) and threshold were studied with 35 undergraduates performing a visual inspection time task and 30 performing a pitch discrimination task. In both tasks, ERP differences related to threshold were temporally localized differences in waveform shape. (SLD)

Results with 54 mice confirm that increased stimulation or usage, as would be provided by environmental enrichment (EE), increases peripheral nerve conduction velocity. These results suggest a role at the physiological level for EE (or deprivation) in affecting measured intelligence. (SLD)

Various experiments demonstrated that the difficulty level of several performance-type intelligence test tasks is determined directly by stimulus and task variables that vary the information to be processed. The implications of these findings for intelligence and the problems of an experimental approach to the measurement of intelligence are…

Three studies involving 16 college students explored cognitive processes reflected by reaction time (RT) and movement time (MT). The hypothesis that correlations of RT and MT with measures of intelligence are due to effects on a common stage of information processing cannot be rejected on the basis of study findings. (SLD)

A conceptual theory for predicting the relations between intellectual abilities and performance during task practice is proposed and is evaluated through an experiment with high school and college students. This macro-theory integrates hierarchical theories of intellectual abilities with information-processing theories of automatic and controlled…