Abstract: Gray’s reinforcement sensitivity theory attempted to explain individual differences of personality through human neurophysiological mechanism. This theory argued that, some subsystems, assumed to come from the central nervous system, were sensitive to signal of reward and punishment stimuli respectively. These subsystems were also assumed to modulate people’s behavior and motivation by their reinforcing effects. To test this theory, several measurements about reinforcement sensitivity were developed, and associated empirical studies were conducted. However, some defects were found around this theory. To remedy these defects, according to the authors, future studies should be devoted: (1) to verify the theory hypotheses by means of physiological measurements; (2) to explore some appropriate personality traits which represent the reinforcement sensitivity; and (3) to investigate the interaction between cognitive and biological factors

Key words: reinforcement sensitivity, behavioral approach system, behavioral inhibition system