TRACX: a recognition-based connectionist framework for sequence segmentation and chunk extraction

Individuals of all ages extract structure from the sequences of patterns they encounter in their environment, an ability that is at the very heart of cognition. Exactly what underlies this ability has been the subject of much debate over the years. A novel mechanism, implicit chunk recognition (ICR), is proposed for sequence segmentation and chunk extraction. The mechanism relies on the recognition of previously encountered subsequences (chunks) in the input rather than on the prediction of upcoming items in the input sequence. A connectionist autoassociator model of ICR, truncated recursive autoassociative chunk extractor (TRACX), is presented in which chunks are extracted by means of truncated recursion. The performance and robustness of the model is demonstrated in a series of 9 simulations of empirical data, covering a wide range of phenomena from the infant statistical learning and adult implicit learning literatures, as well as 2 simulations demonstrating the model's ability to generalize to new input and to develop internal representations whose structure reflects that of the items in the input sequence. TRACX outperforms PARSER (Perruchet & Vintner, 1998) and the simple recurrent network (SRN, Cleeremans & McClelland, 1991) in matching human sequence segmentation on existing data. A new study is presented exploring 8-month-olds' use of backward transitional probabilities to segment auditory sequences.     

Patterns of neuronal activation in the rat brain and spinal cord in response to increasing durations of restraint stress

By most accounts the psychological stressor restraint produces a distinct pattern of neuronal activation in the brain. However, some evidence is incongruous with this pattern, leading us to propose that the restraint-induced pattern in the central nervous system might depend on the duration of restraint used. We therefore determined the pattern of neuronal activation (as indicated by the presence of Fos protein) seen in the paraventricular nucleus (PVN), bed nucleus of the stria terminalis, amygdala, locus coeruleus, nucleus tractus solitarius (NTS), ventrolateral medulla (VLM) and thoracic spinal cord of the rat in response to 0, 15, 30 or 60 min periods of restraint. We found that although a number of cell groups displayed a linear increase in activity with increasing durations of restraint (e.g. hypothalamic corticotrophin-releasing factor (CRF) cells, medial amygdala neurons and sympathetic preganglionic neurons of the thoracic spinal cord), a number of cell groups did not. For example, in the central amygdala restraint produced both a decrease in CRF cell activity and an increase in non-CRF cell activity. In the locus coeruleus, noradrenergic neurons did not display Fos in response to 15 min of restraint, but were significantly activated by 30 or 60 min restraint. After 30 or 60 min restraint a greater degree of activation of more rostral A1 noradrenergic neurons was observed compared with the pattern of A1 noradrenergic neurons in response to 15 min restraint. The results of this study demonstrate that restraint stress duration determines the amount and the pattern of neuronal activation seen in response to this psychological stressor.     

Eyewitness memory following discussion: using the MORI technique with a Western sample

Researchers studying memory conformity have made significant advances in our understanding of the phenomenon, but have used methods with significant shortcomings. Mori's three‐stage method addresses many of these concerns. To date the technique has not been replicated on a Western sample. We present such a study, and discuss two significant improvements to Mori's method. We found that subjects were more likely to report the correct answer for non‐discussed critical details than discussed critical details. Our data also suggested that when subjects agreed with their partner's information during the discussion, they did so because they thought that information was accurate; only a minority of the time did they go along with their partner during discussion and revert to their own answer at the test. We draw parallels between the unknown mechanisms driving memory conformity effects and the search for mechanisms driving the misinformation effect two decades ago. Copyright © 2007 John Wiley & Sons, Ltd.     

Are cross-cultural comparisons of personality profiles meaningful? Differential item and facet functioning in the Revised NEO Personality Inventory

Measurement invariance is a prerequisite for confident cross-cultural comparisons of personality profiles. Multigroup confirmatory factor analysis was used to detect differential item functioning (DIF) in factor loadings and intercepts for the Revised NEO Personality Inventory (P. T. Costa, Jr., & R. R. McCrae, 1992) in comparisons of college students in the United States (N = 261), Philippines (N = 268), and Mexico (N = 775). About 40%-50% of the items exhibited some form of DIF and item-level noninvariance often carried forward to the facet level at which scores are compared. After excluding DIF items, some facet scales were too short or unreliable for cross-cultural comparisons, and for some other facets, cultural mean differences were reduced or eliminated. The results indicate that considerable caution is warranted in cross-cultural comparisons of personality profiles.     

Evaluating the Psychometric Properties of the Teamwork KSA Test

The Teamwork KSA Test has been a welcome addition to the practitioner's selection toolkit as well as a useful measure for teamwork researchers. We analyzed the psychometric properties of the Teamwork KSA Test and recognized correlates of the construct using three samples of working individuals recruited through a university (N = 241, N = 230, N = 332) and found slim evidence for a factor structure of the underlying constructs. Furthermore, classical reliability estimates did not meet traditional psychometric standards. Total TKSA scores predicted self‐ratings and instructor ratings of teamwork in two of the samples; effect sizes were small.     

A cross-modal weapon focus effect: The influence of a weapon's presence on memory for auditory information

To examine whether a weapon's presence impairs witnesses' memory for auditory information (as it impairs memory for visual information), we conducted two experiments in which undergraduates watched one version of a videotape depicting a male target who held either a weapon or a neutral object and conversed with a female character. The semantic content of his remarks was either easy or difficult to comprehend. The weapon's presence did not affect voice identification accuracy or memory for the target's vocal characteristics (e.g., pitch, loudness, speech rate) but did worsen memory for semantic content in the Difficult Comprehension condition. Our results can be explained by multiple resource models of attention, which propose separate resource “pools” for different sensory modalities.     

The Luscher Color Test: An Investigation of Validity and Underlying Assumptions

This experiment investigated several underlying assumptions and one aspect of the validity of the Luscher Color Test, a projective test developed in Europe and relatively unknown in the United States. It was predicted that Ss would report increases in “negative” feelings to the color red, while blue would have the opposite effect, and yellow would produce an increase in “positive” feelings. Twenty-three male and 23 female Ss rated their immediate reactions to the LCT colors on seven mood adjectives, following which they were given the short version LCT and the IPAT Anxiety Scale. The results supported the hypotheses regarding blue and yellow, but not those regarding red nor the validity of the LCT as an anxiety measuring instrument.