The Task Of Masking The Start Affect Erps

Top-down modulation is a function of brain cortex to set behaviors into a special working pattern according to defined task requirements, just as intention, expectancy, task-set and etc.Top-down factors can modulate the controlled processing. And if it can also modulate automatic processing remains to be discussed. Automatic processing includes automatic perceptual activation process, automatic semantic activation process and automatic response activation process. The automatic processing is studied mainly by masked priming paradigm.The thesis mainly concerns whether the factor of task, which includes intention and task-set, can affect the automatic semantic activation process and automatic response activation process. So, two studies involving six experiments were processed to solve this problem by using masked priming paradigm.Study one discussed task's effect on automatic semantic activation process by ERPs and we chose the college students (aging from 20-30) as our subjects. Study one contains experiment one and experiment two.The results of experiment one showed that intention of the task affects masked semantic priming:when the subjects were required to make decisions of living or nonliving things, as in semantic decision, masked primes do affect the processing of targets; when the subjects were required to make decisions of the structure of the Chinese words, as in perceptual decision, masked primes don't affect the processing of targets.The results of experiment two showed that task-set affects masked semantic priming:when the subjects finished making decisions of living or nonliving things, as in semantic processing, subsequently presenting masked primes do affect the processing of targets; when the subjects finished making decisions of the structure of the Chinese words, as in perceptual processing, subsequently presenting masked primes don't affect the processing of targets.Study two discussed task's effect on automatic response activation process by ERPs and behavioral methods. Study two contains experiment three, four, five and six. College students were chosen as subjects in experiment three, four, five and elder people aging from 45-65 were chosen as subjects in experiment six.The results of experiment three showed that under the unconscious condition, intention of the present task can modulate the automatic response activation process. In special tasks, subjects can coupled different features of one kind of stimuli with special response through the instruction, as in S-R rules, and priming effect are biased.The results of experiment four showed that under the unconscious condition, intention that is unrelated to present task can modulate the automatic response activation process. In special tasks, subjects can coupled stimuli of unrelated intention with special response through the instruction, as in S-R rules, and priming effect of the present task are biased.The results of experiment five showed that under the unconscious condition, intention that is unrelated to present task can modulate the automatic response activation process. In special tasks, subjects can coupled all the stimuli of unrelated intention with special response through the instruction, as in S-R rules, and priming effect of the present task are biased.The results of experiment six showed that unrelated intention cannot bias the automatic response priming effect of the present task among the group of elder people who are form 45-60 years old.The main conclusion of the research is top-down modulation can modulate the automatic semantic activation and automatic response activation process.