Detection and recognition: Concurrent processes in perception

In two experiments, event-related brain potentials (ERPs) were recorded while subjects performed a simultaneous detection and recognition task. Ten subjects listened to pure tones in noise and reported both whether a target tone had occurred (using a four-category confidence rating scale) and whether the target was one of two (Experiment 1) or four (Experiment 2) tones differing in frequency. The amplitudes of three ERP components were found to be differentially related to detection and recognition performance. The early N100 component varied with processing related only to detection, while the late P300 varied with both detection and recognition, and a later slow positive shift varied only with recognition and not with detection. While the latenciee of both N100 and P300 increased for less confident target detections, there were no differences in the latencies of these ERP components between correctly and incorrectly identiffed targets. Recognition performance was above the level expected by chance even when subjects reported that no target had been presented. The results indicate that brain potential components can be used to disclose temporal features of the processing of a stimulus by the nervous system and support the view that detection and recognition are partially independent, concurrent processes in perception.     

Anatomic Magnetic Resonance Imaging of the Developing Child and Adolescent Brain and Effects of Genetic Variation

Magnetic resonance imaging studies have begun to map effects of genetic variation on trajectories of brain development. Longitudinal studies of children and adolescents demonstrate a general pattern of childhood peaks of gray matter followed by adolescent declines, functional and structural increases in connectivity and integrative processing, and a changing balance between limbic/subcortical and frontal lobe functions, which extends well into young adulthood. Twin studies have demonstrated that genetic factors are responsible for a significant amount of variation in pediatric brain morphometry. Longitudinal studies have shown specific genetic polymorphisms affect rates of cortical changes associated with maturation. Although over-interpretation and premature application of neuroimaging findings for diagnostic purposes remains a risk, converging data from multiple imaging modalities is beginning to elucidate the influences of genetic factors on brain development and implications of maturational changes for cognition, emotion, and behavior.     

Sex,sex roles,and response styles for negative affect: Selectivity in a free recall task

Study 1 examined how responses to negative affect may be influenced by sex differences in response styles [S. Nolen-Hoeksema (1987), “Sex Differences in Unipolar Depression: Evidence and Theory,” Psychological Bulletin, Vol. 101, pp. 259–282] and situational norms. Male and female experimental subjects were led to experience negative affect by reading and rating sad stories, and were then given either nonnormative or normative feedback. Nonnormative subjects were informed that their story ratings were more negative than other participants' ratings. Normative subjects were informed that their ratings were similar to others' ratings. For nonnormative subjects, men recalled less negative material than women, suggesting that response styles are most apparent when negative affect is considered inappropriate. As both sex and sex role orientation are predictive of response styles, Study 2 examined the hypothesis that both sex and sex role orientation are predictive of recall in a manner similar to sex in Study 1. Male and female subjects high and low in masculinity and femininity were assigned to negative-nonnormative and neutral affect conditions. In addition to a marginally significant sex effect consistent with Study 1, results revealed that high-masculinity individuals tended to recall more positive material in the negative-nonnormative condition than in the neutral affect condition. In contrast, low-masculinity individuals recalled less positive material in the negative-nonnormative condition than in the neutral affect condition. The implications of this research for the impact of negative affect on recall are addressed.     

Empirical evidence for narrative structure

Three experimental tasks—spontaneous telling of a story, reading, and parsing the story—were used to determine whether empirical data reflect the narrative structure of stories and can be predicted by a plot unit analysis of the stories (Lehnert, 1981). It was found that spontaneous pause durations at sentence breaks were highly correlated with the importance of these breaks as predicted theoretically. Only low correlations were obtained, however, when reading pause durations were correlated with the model. As for parsing values, the value of the correlation coefficients depended on whether stories had sufficient superficial linguistic cues to help the subjects in parsing. It was concluded that spontaneous pausing not only reflects the narrative structure of stories, but can be used as a guide to constructing theories of narrative structure as well as for deciding between competing theories.