 Also, his research into augmenting/reducing of the cortical evoked potential provided a reliable model of brain functioning in high and low sensation seekers.Zuckerman spent sabbaticals with eminent colleagues Hans Eysenck, Jeffrey Gray, and Robert Plomin, in England, where factor analytic studies showed that a combination of impulsivity and sensation seeking formed a reliable personality dimension.In 1975, Zuckerman commenced a series of presentations at international meetings in Europe.