Natural history of the long-term cognitive, affective, and physical sequelae of mild traumatic brain injury

Mild traumatic brain injury (MTBI) is associated with cognitive,affective, and physical sequelae. When symptoms persist for more than 3 months, a diagnosis of Post-Concussion Syndrome (PCS) is often given. The current study tracked symptom development to explore the natural sequelae of MTBI. Twenty-six MTBI patients received a comprehensive neuropsychological assessment at three intervals: within 1 week, at 4 months and at 7 months post-concussion. Based on DSMIV criteria and clinical judgment, two external raters diagnosed five MTBI participants with PCS. Results suggested that aspects of cognitive functioning of the symptomatic MTBI (i.e., PCS) participants were different from matched normal control (NC) subjects, and from the 21 MTBI patients who were asymptomatic, at 4 months. Asymptomatic MTBI participants improved in overall level of functioning from 4 to 7 months, but remained significantly different from NC participants in their reduced verbal fluency and working memory functioning.     

The control of saccade trajectories: direction of curvature depends on prior knowledge of target location and saccade latency

Recent reports have shown that saccades can deviate either toward or away from distractors. However, the specific conditions responsible for the change in initial saccade direction are not known. One possibility, examined here, is that the direction of curvature (toward or away from distractors) reflects preparatory tuning of the oculomotor system when the location of the target and distractor are known in advance. This was investigated by examining saccade trajectories under predictable and unpredictable target conditions. In Experiment 1, the targets and the distractors appeared unpredictably, whereas in Experiment 2 an arrow cue presented at fixation indicated the location of the forthcoming target prior to stimulus onset. Saccades were made to targets on the horizontal, vertical, and principal oblique axis, and distractors appeared simultaneously at an adjacent location (a separation of +/- 45 degrees of visual angle). On average, saccade trajectories curved toward distractors when target locations were unpredictable and curved away from distractors when target locations were known in advance. There was no overall difference in mean saccade latencies between the two experiments. The magnitude of the distractor modulation of saccade trajectory (either toward or away from) was comparable across the different saccade directions (horizontal, vertical, and oblique). These results are interpreted in terms of the time course of competitive interactions operating in the neural structures involved in the suppression of distractors and the selection of a saccade target. A relatively slow mechanism that inhibits movements to distractors produces curvature away from the distractor. This mechanism has more time to operate when target location is predictable, increasing the likelihood that the saccade trajectory will deviate away from the distractor.     

Dual route for subtask order control: Evidence from the psychological refractory paradigm

A change in subtask order in the psychological refractory period (PRP) paradigm increases the effect of stimulus onset asynchrony (SOA) on the second response. We used a paradigm with cued, randomly determined subtask order to test the hypothesis that this SOA by order switch overadditivity reflects order control, via “copying” stimulus order. In Experiments 1a and 1b, overadditivity was evident only with insufficient opportunity for cue-based order control. In Experiment 2, overadditivity was decreased by using the same set of stimuli in the two subtasks, presumably by removing the opportunity to rely on stimulus order. In Experiment 3, removing the order cue increased the overadditivity, presumably because control was based solely upon copying stimulus order. The results indicate interactive top-down and bottom-up order control. Implications to theories of the PRP paradigm are discussed.     

Native Thai Speakers’ Acquisition of English Word Stress Patterns

The influence of syllabic structure, lexical class and stress patterns of known words on the acquisition of the English stress system was investigated in ten native Thai speakers. All participants were adult learners of English with an average length of residence in the US of 1.4 years. They were asked to produce and give perceptual judgments on 40 English non-words of varying syllabic structures in noun and verb sentence frames. Results of the production data suggested that syllables with a long vowel attracted stress more often than syllables containing a short vowel and nouns received initial stress more often than verbs. Additionally, regression analyses with the three factors as predictors suggested that Thai participants’ pattern of stress assignment on non-words was significantly influenced by the stress patterns of phonologically similar real words. These results were compared and contrasted to those found in previous work with Spanish–English and Korean–English bilinguals.     

Sex-role-related differences in self-concept and mental health

Examined the differences in serf-concept and psychological health between androgynous, sex-typed, cross-sex-typed, and undifferentiated males and females. Two hundred forty-nine students who were enrolled in introductory psychology classes were classified according to sex type on the basis of their scores on the Bem Sex-Role Inventory. Nine aspects of self-concept and five aspects of psychological health, obtained, from the Tennessee Self-Concept Scale, were analyzed as a function of Sex and Sex Type. A series of analyses of variance and subsequent individual comparisons across groups revealed a clear pattern wherein androgynous subjects manifested more positive self-concepts and more positive psychological health than sex-typed subjects. Undifferentiated subjects manifested the poorest self-concepts, while results for sex-typed and cross-sex-typed subjects varied more as a function of the sex of the subject. The data are discussed as appearing to be consistent with Bem's hypothesis that androgynous people may represent a more appropriate societal definition of mental health than strongly sex-typed people. Qualifications of this support are also discussed.     

False memories and lexical decision: even twelve primes do not cause long-term semantic priming

Semantic priming effects are usually obtained only if the prime is presented shortly before the target stimulus. Recent evidence obtained with the so-called false memory paradigm suggests, however, that in both explicit and implicit memory tasks semantic relations between words can result in long-lasting effects when multiple 'primes' are presented. The aim of the present study was to investigate whether these effects would generalize to lexical decision. In four experiments we showed that even as many as 12 primes do not cause long-term semantic priming. In all experiments, however, a repetition priming effect was obtained. The present results are consistent with a number of other results showing that semantic information plays a minimal role in long-term priming in visual word recognition.