Previous studies have found that reward effect is stronger for more difficult to retrieve items, but whether this effect holds true for the associative memory remains unclear too. We investigated the effects and neural mechanisms of the different unitization depths and reward sets on encoding associative memory using event-related potentials, which were recorded through a Neuroscan system with a 64-channel electrode cap according to the international 10–20 system, and five electrodes were selected for analysis. Thirty healthy college students took part (...) in this study. During encoding, participants were carried out two encoding tasks, a congruity-judgment task with high unitization and a color-judgment task with low unitization, with half of the items rewarded. The test phase was conducted immediately after the encoding phase. The results for false alarm rates and Prs in relational retrieval revealed that the reward differences in the color-judgment task were greater than those in the congruity-judgment task. The ERP results further showed significant reward effects at P300 and LPP in the color-judgment task both for intact and rearranged items, and the reward effects at LPP were distributed more widely than the reward effects at P300 in the color-judgment task. These results suggest that reward provided a greater boost when retrieving associative memory of low unitized items. (shrink)

Previous studies have found differences in the cognitive and neural mechanisms between cognitive reappraisal and expression suppression in the regulation of various negative emotions and the recognition of regulated stimuli. However, whether these differences are valid for sadness remains unclear. As such, we investigated the effect of cognitive reappraisal and expression suppression on sadness regulation and the recognition of sad scenes adopting event-related potentials. Twenty-eight healthy undergraduate and graduate students took part in this study. In the regulation phase, the participants (...) were asked to down-regulation, expressive suppression, or maintain their sad emotion evoked by the sad images, and then to perform an immediately unexpected recognition task involving the regulated images. The behavioral results show that down-regulation reappraisal significantly diminished subjective feelings of sadness, but expressive suppression did not; both strategies impaired the participants’ recognition of sad images, and expressive suppression had a greater damaging effect on the recognition of sad images than down-regulation reappraisal. The ERP results indicate that reappraisal and expressive suppression significantly reduced the late positive potential induced by sadness. These findings suggest that down-regulation reappraisal and expression suppression can effectively decrease sadness, and that down-regulation reappraisal is a more effective regulation strategy for sadness. Both strategies impair the recognition of sad scenes, and expression suppression leads to relatively greater impairment in the recognition of sad scenes. (shrink)