Enhancement Effects Of Emotional Memory: Automatic And Control Coding Processing

The phenomenon that emotional stimuli are better remembered than neutral ones is called Emotionally Enhanced Memory Effect (EEM effect). Previous studies revealed that EEM effect is influenced by the valence and arousal of emotional stimuli, and EEM effects relied on arousal and valence are mediated by distinct neuro routes, especially negative emotional stimuli. The EEM effect relied on arousal is mainly mediated by the amygdale-hippocampal network and the EEM effect relied on valence is supported by a PFC-hippocampal network. Based on the distinct neuro routes of EEM effect, Kensinger and Corkin (2004) preposed an associative pattern on EEM effect, namely the EEM effect relied on arousal is associated with automatic encoding processing, while the EEM effect relied on valence is associated with controlled encoding processing because the processing in the amygdale-hippocampal route is less affected by attention, and reflects an relatively automatic processing, but the processing in the PFC-hippocampal route is mainly associated with rehearsal and elaboration, and reflects a controlled processing (Kensinger&Corkin,2003;2004; Kensinger,2004). Moreover, the behavioral data with negative words by Kensinger and Corkin (2004) supported this associative pattern that the EEM effect relied on arousal is associated with automatic encoding processing and the EEM effect relied on valence is associated with controlled encoding processing.However, Kensinger and Corkin's study (2004) did not examine how automatic and controlled processing contributed the EEM dependent on arousal and valence in a positive stimuli condition, thus more evidence is needed to clarify whether the observed association that occurred with negative emotional stimuli is replicable with positive emotional stimuli. In addition, the distinct neural mechanisms do not necessarily correspond with the automatic and controlled processing in behavioral performance because the EEM of arousing stimuli does not solely depend on activation in the amygdala, and the EEM of nonarousing stimuli does not solely depend on prefrontal activation. Recently, related researchers examined the cognitive processing mechanisms of EEM effect from a behavioural perspective, and found that EEM effect is the result of combination of automatic and controlled processing. But these studies simply investigated the effect of emotionality on EEM effect and did not distinguish the EEM effects reliedt on arousal and valence (Talmi et al.,2007,2012; Kern et al.,2005; Chainay et al.,2012Maddox et al.,2012). Therefor, it is unclear whether or not the EEM dependent on arousal is associated with automatic encoding processing and whether or not the EEM dependent on valence is associated with controlled encoding processing. More evidence is needed to support this associative pattern.Based on the above reasons, study I in which negative/positive arousing words, negative/positive nonarousing and neutral words were used as stimuli materials, and study ? in which negative/positive arousing pictures, negative/positive nonarousing and neutral pictures were used as stimuli materials, examined the EEM effects relied on arousal and valence and their relation with automatic or controlled processing respectively under the auditory and optical divided attention conditions, using the learning?recognition and divided attention (DA) paradigms. The results of corrected recognition rates and discriminability (d') consistently shown that the EEM relied on valence was supported by controlled encoding processing, but for positive emotional stimuli, the encoding processing underlying the EEM effect relied on arousal was different with negative emotional ones. The former belonged to controlled encoding processing, and the latter belonged to automatic encoding processing. These results did not completely support the associative pattern proposed by Kensinger and Corkin (2004).The differences in encoding processes between positive and negative emotional stimuli may be due to different biological information carried two kinds of emotional stimuli. Related studied (Gable&Harmon-Jones,2008a,2010b,2010c) revealed that the biological information or motivational intensity carried emotional stimuli is a potential moderator variable affecting emotional memory. Emotion with high motivational intensity narrows cognitive processes, and emotion with low motivational intensity broadens cognitive processes. Therefore, study III in which high avoidance-/approach-motivational pictures, low avoidance-/approach-motivational pictures and neutral pictures were used as stimuli materials, examined the EEM effect relied on motivational intensity and its relation with automatic or controlled processing based on emotional motivational dimensional model. Delicious pictures were used to induce high approached-motivation positive emotion in present study. The experiment was conducted with the relatively hunger participants in order to keep them desire for delicious pictures. The results found that the EEM effect relied on motivational intensity (regardless of approach or avoidance) belongs to automatic encoding processing.Based on the above studies, the present paper concludes as the following:(1) The EEM effects relied on arousal and valence are observed under FA condition, and not affected by gander.(2) The EEM effect relied on motivational intensity is observed under FA condition as well.(3) The EEM effect relied on valence is supported by controlled encoding processing.(4) The EEM effect relied on arousal is mediated by the valence of the stimuli, which is associated with automatic encoding processing for negative stimuli, but controlled encoding processing for positive stimuli.(5) The EEM effect relied on motivational intensity is associated automatic processing.