Recruitment modeling applied to longitudinal studies of group differences in intelligence

In longitudinal studies data is collected in a series of waves. Each wave after the first suffers from attrition. Therefore it can be difficult to discriminate between changes in sample parameters due to a longitudinal process (e.g. ageing) and changes due to attrition. The problem is particularly vexing if one of the purposes is to compare differences between two or more groups over time, because there may be differential attrition across groups. We refer to this as a recruitment problem, because the sample studied in any wave after the first can be thought of as having been recruited from a preceding wave. We present a mathematical model of the recruitment process. We then apply it to two large longitudinal studies, the British Cohort Survey 1970 and the National Child Development Study (1958), to demonstrate how we can identify effects expected from recruitment alone. As an illustration we show that differential recruitment would predict increasing differences between estimates of men's and women's intelligence as the studied sample ages.     

Anchoring in a novel bimanual coordination pattern

Anchoring in cyclical movements has been defined as regions of reduced spatial or temporal variability [Beek, P. J. (1989). Juggling dynamics. PhD thesis. Amsterdam: Free University Press] that are typically found at movement reversal points. For in-phase and anti-phase movements, synchronizing reversal points with a metronome pulse has resulted in decreased anchor point variability and increased pattern stability [Byblow, W. D., Carson, R. G., & Goodman, D. (1994). Expressions of asymmetries and anchoring in bimanual coordination. Human Movement Science, 13, 3-28; Fink, P. W., Foo, P., Jirsa, V. K., & Kelso, J. A. S. (2000). Local and global stabilization of coordination by sensory information. Experimental Brain Research, 134, 9-20]. The present experiment examined anchoring during acquisition, retention, and transfer of a 90 degrees phase-offset continuous bimanual coordination pattern (whereby the right limb lags the left limb by one quarter cycle), involving horizontal flexion about the elbow. Three metronome synchronization strategies were imposed: participants either synchronized maximal flexion of the right arm (i.e., single metronome), both flexion and extension of the right arm (i.e., double metronome within-limb), or flexion of each arm (i.e., double metronome between-limb) to an auditory metronome. In contrast to simpler in-phase and anti-phase movements, synchronization of additional reversal points to the metronome did not reduce reversal point variability or increase pattern stability. Furthermore, practicing under different metronome synchronization strategies did not appear to have a significant effect on the rate of acquisition of the pattern.     

Interpretation of Ambiguous Information in Girls at Risk for Depression

Research has consistently documented that depressed individuals process information in a negatively biased manner. There is little evidence, however, concerning whether these biases represent risk factors for depression, as is hypothesized by cognitive models. In the present study we investigated whether a particular cognitive bias observed in currently depressed individuals, the tendency to interpret ambiguous information negatively, characterizes daughters of depressed mothers, a population known to be at increased risk for depression. Following a negative mood induction, young daughters of depressed and never-disordered mothers completed two information-processing tasks in which their interpretations of emotionally ambiguous stimuli were evaluated. Daughters of depressed mothers interpreted ambiguous words more negatively and less positively, and ambiguous stories more negatively, than did daughters of never-disordered mothers. These results provide support for cognitive vulnerability models of depression.     

Temporal dynamics of masked word reading

The repercussions of unconscious priming on the neural correlates subsequent cognition have been explored previously. However, the neural dynamics during the unconscious processing remains largely uncharted. To assess both the complexity and temporal dynamics of unconscious cognition the present study contrasts the evoked response from classes of masked stimuli with three different levels of complexity; words, consonant strings, and blanks. The evoked response to masked word stimuli differed from both consonant strings and blanks, which did not differ from each other. This response was qualitatively different to any evoked potential observed when stimuli were consciously visible and peaked at 140ms, earlier than is usually associated with differences between words and strings and 100ms earlier than word-consonant string differences in the visible condition. The evoked response demonstrates a qualitatively distinct signature of unconscious cognition and directly demonstrates the extraction of abstract information under subliminal conditions.     

Bilateral disadvantage: lack of interhemispheric cooperation in schizophrenia

Language anomalies and left-hemisphere dysfunction are commonly reported in schizophrenia. Additional evidence also suggests differences in the integration of information between the hemispheres. Bilateral gain is the increase in accuracy and decrease in latency that occurs when identical information is presented simultaneously to both hemispheres. This study measured bilateral gain in controls (n=20) and individuals with schizophrenia (n=10) using a lexical-decision task where word or non-word judgements were made to letter strings presented in the left visual field (LVF), right visual field (RVF) or bilaterally (BVF). Language was not abnormally lateralized in the schizophrenia group. Controls exhibited the expected decrease in latency when words were presented bilaterally. This effect was not observed in the schizophrenia group who were actually disadvantaged in this condition. The lack of bilateral gain in schizophrenia is discussed as arising from differences in the connections between areas in each hemisphere that mediate language.     

Selective attention to emotional faces following recovery from depression

This study was designed to examine attentional biases in the processing of emotional faces in currently and formerly depressed participants and healthy controls. Using a dot-probe task, the authors presented faces expressing happy or sad emotions paired with emotionally neutral faces. Whereas both currently and formerly depressed participants selectively attended to the sad faces, the control participants selectively avoided the sad faces and oriented toward the happy faces, a positive bias that was not observed for either of the depressed groups. These results indicate that attentional biases in the processing of emotional faces are evident even after individuals have recovered from a depressive episode. Implications of these findings for understanding the roles of cognitive and interpersonal functioning in depression are discussed.     

Mood regulation in depression: Differential effects of distraction and recall of happy memories on sad mood

Recent research suggests that the recall of positive memories plays an important role in mood regulation. In this study, the authors examined the ability of currently depressed, formerly depressed, and never-depressed participants to regulate sad mood through the recall of positive memories or through distraction. Although improvement in mood was found for all participants in response to distraction, under instructions to recall positive memories, never-depressed participants' moods improved, whereas formerly depressed participants' sad moods remained unchanged. It is important to note that depressed participants exhibited a worsening of their sad moods after recalling positive memories. These results suggest both that depression is associated with an impaired ability to use positive recall to regulate a sad mood and that this impairment continues to be evident following recovery.     

Organization of sex-typical patterns of defense during food protection in the rat: The role of the opponent's sex

Feeding rats defend a food item from an approaching conspecific by turning away, laterally, about 180°. Females and males use a different composition of movements and stepping patterns to perform these defensive dodges. This study was designed to examine the role of the robber's sex on the execution of sex-typical patterns of dodging. All subjects were tested with a partner of each sex. During dodging, females used the female-typical pattern of pivoting around the pelvis, and males used the male-typical midbody pivot, irrespective of the robber's sex. These findings show that the sex-typical patterns of dodging are not determined by the sex of the partner. Females and males however, differed in how they were oriented towards a same sex robber at the end of the dodge. This suggests that while male and female robbers must pose different defensive problems, these differences are dealt with by modifying the sex-typical pattern of dodging rather than by switching to the dodge pattern of the opposite sex. This further suggests that the differences in the composition of the dodge pattern in males and females are not due to extrinsic contingencies, but rather, are due to intrinsic differences in the sex-typical organization of defensive motor patterns. Aggr. Behav. 23:197–214, 1997.© 1997 Wiley-Liss, Inc.     

Violence in the community—a study of violence and aggression in homelessness and mental health day services

This study examined violence and aggression in five agencies providing day services in homelessness or mental health. Incident reporting was used to test the hypotheses that aggression is associated with alcohol problems, drug use, mental disorder, homelessness, history of violence, age and sex. Agency policies and patterns to aggressive incidents were explored. Three agencies provided a sufficient number of incidents for analysis (involving 30 ‘aggressors’). A history of violence was associated with aggression in all three agencies; alcohol problems, drug use and younger age were associated with aggression in at least one agency; no association was found for mental disorder, homelessness or sex. A degree of pattern to incidents could be discerned, with drink or drugs often involved, and exercises of authority or intervention in client altercations being particularly likely to precede aggression towards staff. A variety of incidents were reported, from verbal arguments to threats with a knife and serious physical assault. © 1997 John Wiley & Sons, Ltd.     

Revisiting the predictive validity of emotional intelligence: self-report versus ability-based measures

In response to general press assertions that training emotionally intelligent children will lead to great rewards, this study examined the relationship between emotional intelligence (EI) and academic achievement in college students, using both self-report and ability-based measures of EI. Specifically, the Mayer, Salovey, Caruso Emotional Intelligence Test (MSCEIT, an ability-based measure) and the Bar-On Emotional Quotient Inventory (EQ-i, a self-report measure) were used to predict academic achievement. Achievement was operationalized as the respondents’ cumulative GPA. Results indicated that EI is not a strong predictor of academic achievement regardless of the type of instrument used to measure it. However, a construct validity examination revealed that the MSCEIT correlated highly with indices of cognitive ability but minimally with personality dimensions. In contrast, the EQ-i failed to correlate with indices of cognitive ability but correlated substantially with numerous personality dimensions.