Working memory is an impartment cognitive function for human being which can maintain and process limited information temporally. Inhibition of working memory plays a role to other cognitions based on working memory. It is important to study the mechanism of inhibition to interference. Proactive interference paradigm is used to study working memory in many studies. Previous researches made proactive interference by control the present times of probe stimulus-use current probe stimulus as target stimulus for the last trail. But, the stimulus that do not present last trail was presented several times before because the number of letter is limited. Then there is no pure control condition without lure under this design. In addition, when the duration of maintain change the memory traces will change too, but there is no research investigate the effect of different retention intervals. To resolve two problems mentioned, we use delayed matching-to-sample paradigm and the stimulus are Chinese character. Participants are asked whether the prober stimulus is same to target stimulus. The interference is evoked by similarity between probe and target stimulus. Furthermore, we use two type of retention intervals (3s & 9s) to investigate whether the same mechanisms underlie inhibition of working memory at different intervals. This study include two experiments, the first one is a behavior experiment to test whether this new paradigm can also cause interfering effect. As expected, this paradigm is same to recent-probe task, n-back task and directed-forgetting task and can increase reaction time and decrease accuracy. Moreover, we found that the performance is better when the interval is 9 seconds. We call it interval effect. Then, based on this experiment we make another one which record participants’ EEG to study the neurological mechanism of interfering effect and interval effect. Amplitude of FN400 under familiar negative condition (probe stimulation is not match target stimulation but it is similar to target stimulation) is less then unfamiliar negative condition (probe stimulation is nether match target stimulation nor similar to target stimulation). This is an ole-new effect and familiar interference is inhibited at the mean time. Furthermore, we find N170 at parietal-occipital area was larger when the interval is 9 seconds then 3 seconds. This indicates that when the interval is long participants pay more attention to probe stimulation in the early stage to resolve interference. This is different from the short interval condition that participants inhibit interference only by inhibit familiarity. Therefore, interval effect is found in this study.
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