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Abstract: The ability to detect and cope with unpredictable novel events is fundamental for adapting to a rapidly changing environment and ensuring the survival of the organism. Despite knowledge of gender differences in emotional processing, little is currently known about the impact of gender on neural processing of emotion-irrelevant, novel stimuli. Using two modified three-stimulus oddball tasks and event-related potentials (ERPs), the present study investigated the impact of sex on brain processing of novel events and the associated neurophysiological correlates. With novel and non-novel control stimuli used as task-irrelevant distracters, Experiment 1 showed higher novelty rating scores and larger size of novelty effects in brain potentials at 200–300ms and 300–430ms time intervals in females compared to males. After excluding the contribution of stimulus probability, Experiment 2 continued to display significant novelty effects in the response times and the amplitudes of the 130–500ms time windows. Most importantly, females displayed a sustained novelty effect in the late positive component (LPC) amplitudes of the 500–600ms interval, which was not observed in males. Therefore, Experiment 1 and 2 demonstrated that females are equipped with enhanced brain processing of emotion-irrelevant, novel stimuli. This phenomenon is independent of the established gender difference in infrequent stimulus processing. We suggest that our findings reflect the differential adaptive demands on females and males during evolution. [Copyright &y& Elsevier]

Abstract: Though the humans are more susceptible to unpleasant stimuli of higher intensity, how the valence intensity of unpleasant stimuli impacts subsequent cognitive processing, and whether this impact increases with the unpleasantness, require clarification. For this purpose, event-related potentials (ERPs) were recorded for highly negative (HN), mildly negative (MN) and neutral cueing pictures, and subsequently for the non-emotional target picture while subjects were required to discriminate the location of the target. Cue-induced ERPs showed more negative deflections for the HN than for the neutral pictures in the 450–650ms time interval. The emotion effect for the MN cueing stimuli, however, was non-significant in this interval. In contrast, target-induced P3 amplitudes were significantly more negative following MN versus neutral cueing pictures, while the P3 amplitudes were not significantly different between HN and neutral conditions, irrespective of cueing validity. Thus, despite weak immediate impact, MN stimuli influenced subsequent target processing more heavily than HN stimuli. This suggests that the impact of unpleasant events on cognition doesn''t necessarily increase with the unpleasantness. Mild unpleasant stimulus, which is weak in immediate emotion arousal, should not be neglected due to the likelihood of producing a sustained impact. [Copyright &y& Elsevier]

Abstract: The recognition potential (RP), which is recorded at occipital–temporal sites 200–300 ms poststimulus onset, is an event-related potential (ERP) response to a recognizable stimulus during an object recognition task. Using the rapid stream stimulation (RSS) paradigm and a word detection task, the present study investigated the effect of word detection on RP activity by manipulating angular orientation and image version of Chinese characters. The results showed larger RP amplitude during the normal condition than during the mirror-reversed condition across angular orientations. Moreover, the RP latencies were delayed for 60°, 120°, and 180° orientations relative to the upright, and the amplitudes were larger for 0° and 60° orientations than for 120° and 180° orientations only during the normal condition. This suggests that, as mirrored by RP activity, different strategies depend on the difficulty of word recognition. More specially, piecemeal and serial processing strategy would be used when incoming information is sufficient for word recognition, whereas holistic strategy and the global analysis of categorical features would be used when a word cannot be recognized due to the degraded quality of incoming stimuli. [Copyright &y& Elsevier]

Abstract: The present study investigates the human brains′ sensitivity to the valence strength of emotionally positive and negative chinese words. Event-Related Potentials were recorded, in two different experimental sessions, for Highly Positive (HP), Mildly Positive (MP) and neutral (NP) words and for Highly Negative (HN), Mildly Negative (MN) and neutral (NN) words, while subjects were required to count the number of words, irrespective of word meanings. The results showed a significant emotion effect in brain potentials for both HP and MP words, and the emotion effect occurred faster for HP words than MP words: HP words elicited more negative deflections than NP words in N2 (250–350ms) and P3 (350–500ms) amplitudes, while MP words elicited a significant emotion effect in P3, but not in N2, amplitudes. By contrast, HN words elicited larger amplitudes than NN words in N2 but not in P3 amplitudes, whereas MN words produced no significant emotion effect across N2 and P3 components. Moreover, the size of emotion-neutral differences in P3 amplitudes was significantly larger for MP compared to MN words. Thus, the human brain is reactive to both highly and mildly positive words, and this reactivity increased with the positive valence strength of the words. Conversely, the brain is less reactive to the valence of negative relative to positive words. These results suggest that human brains are equipped with increased sensitivity to the valence strength of positive compared to negative words, a type of emotional stimuli that are well known for reduced arousal. [Copyright &y& Elsevier]