Implicit Effects of Emotional Contexts

It was investigated if ERP differences are dependend of explicit item recognition by comparing ERP's caused by test items that were either encoded as negatively emotional or neutral study contexts and the question of whether items were classified in a correct manner or misclassified as new (Jaeger and Rugg, 2012). The pictures that were used were 300 emotionally neutral, which were the critical items, and there were also 200 emotional background contexts differing in valence and arousal. During the phase when participants had to encode, the 200 contexts were given and they were associated with 200 critical items. The other 100 items were used as "new" items in the test. After the phase of encoding, the test phase was conducted twentyfour hours afterwards. The task of the participants was to press a button when the test item was seen in the phase of encoding, and another button when participants thought that the test item was new. During this test phase ERP's were recorded.

The findings of the behavioral data showed that the participants were more correct in the rejection of new test items rather than endorsing old test items that they studied in the negative and neutral situations in a correct manner.

The ERP analysis was done in three parts. First, differences in ERP amplitude were compared for correctly classified old test items and rejected new items based on the emotional status of the old item. The second stage contrasted the studied items that were incorrectly classified as new for the ability to find emotional memory effects while explicit recognition was absent. The last analysis consisted of contrasting emotionally related hits as compared to misses in order to find possible disparities among explicit and implicit item retrieval.

The results of the event related potentials showed that there was an old-new effect in which correctly recognized items had more positive ERP's as compared to successfully rejected items. These old-new effects were already seen as soon as 200 milliseconds after the onset of the stimulus. Furthermore, it became evident that an analysis that was for the 300-500 ms and 500-800 ms range were apparent in both emotional as well as neutral hits. The authers interpret these findings as instances of the midfrontal and parietal old-new effects (Jaeger and Rugg, 2012). A direct comparison among emotional and neutral hits revealed differences in retrieval associated latencies of 200-300 ms and 800-1,100 ms.