Time does not cause forgetting in short-term serial recall

Time-based theories expect memory performance to decline as the delay between study and recall of an item increases. The assumption of time-based forgetting, central to many models of serial recall, underpins their key behaviors. Here we compare the predictions of time-based and event-based models by simulation and test them in two experiments using a novel manipulation of the delay between study and retrieval. Participants were trained, via corrective feedback, to recall at different speeds, thus varying total recall time from 6 to 10 sec. In the first experiment, participants used the keyboard to enter their responses but had to repeat a word (called the suppressor) aloud during recall to prevent rehearsal. In the second experiment, articulation was again required, but recall was verbal and was paced by the number of repetitions of the suppressor in between retrieval of items. In both experiments, serial position curves for all retrieval speeds overlapped, and output time had little or no effect. Comparative evaluation of a time-based and an event-based model confirmed that these results present a particular challenge to time-based approaches. We conclude that output interference, rather than output time, is critical in serial recall.     

Death in the family and HIV risk-taking among intravenous drug users

The objective of this study was to ascertain the relationship among intravenous drug users between high levels of HIV risk-taking and both (a) deaths of significant others experienced before age 15, and (b) unresolved mourning; 592 out-of-treatment intravenous drug users (71.4% male; mean age = 40.5), stratified as to zip code, were recruited in San Jose, CA, as part of a CDC multisite investigation of access to sterile needles and HIV infection. HIV serostatus tests were obtained and an individual, structured interview administered covering demographics, employment, mental health, HIV risk-taking behavior, family contacts/closeness, and family deaths/mourning. Multivariate analyses indicated that the extent of HIV risk-taking in adulthood was highly and positively related to (a) the number of close-family-member deaths participants experienced as youth, (b) the extent to which respondents effectively mourned sudden family losses, (c) the extent to which those lost were emotionally close to the respondent, and (d) whether or not the respondent attended the funerals of lost relatives. Canonical correlations between sets of death/mourning and HIV risk-taking variables were .55 for the total sample (p < .001) and .70 for the subsample who experienced early and sudden family deaths (p < .001). In both analyses, it made little difference if age and gender were partialed out. These findings give credence to the importance of (a) unexpected deaths experienced early in life, and (b) related, inadequate mourning, as factors in progressively higher adult HIV risk-taking. They suggest that treatment for such individuals and their families should involve grief work dealing with unresolved losses within the family of origin. In addition, prevention efforts may have to revise their modus operandi toward both more focused and more family-based methods of outreach and engagement.     

A cautionary tale of two statistics: partial correlation and standardized partial regression

Partial correlation and standardized partial regression are widely used to control for other variables in cross-sectional and longitudinal studies. Two aspects of these statistics can radically alter the interpretation of data and so deserve attention. First, their sign will be opposite to that of the original zero-order correlation when this correlation is of the same sign as and smaller than the product of the other 2 correlations. Second, their size will be considerably larger than a weak zero-order correlation when either that correlation is positive and the product of the other 2 correlations is negative or that correlation is negative and the product of the other 2 correlations is positive. The first aspect is illustrated with data from J. M. Gottman and L. J. Krokoff (1989) on initial conflict behavior and initial and later marital satisfaction, and the 2nd aspect is illustrated with data from C. L. Heavey, C. Layne, and A. Christensen (1993) on the same issue. Their interpretation of their findings is questioned.     

A Multilevel Contextual Model of Neighborhood Collective Efficacy

Different data sources were used to examine hypothesized relations among neighborhood-, family-, and individual-level variables, and perceptions of neighborhood collective efficacy. Data were from 1,105 individuals (56% female, 42% African American, and 58% White) nested within 55 neighborhoods and 392 families, analyzed within a multilevel design using a 3-level model. At the neighborhood level, the study examined relations between Census, police, and neighborhood representative indicators. At the family level, the model examined the influence of marital status and family income. At the individual level, gender and age were examined. Results indicated that age at the individual level, marital status at the family level, and poverty and perceived gang activity at the neighborhood level predicted levels of neighborhood collective efficacy. The study illustrated significant variation across neighborhoods and families, and demonstrates the utility of combining different sources of neighborhood data to examine relations of interest within a multilevel framework.     

Stereotype susceptibility narrows the gender gap in imagined self-rotation performance

Three studies examined the impact of stereotype messages on men’s and women’s performance of a mental rotation task involving imagined self-rotations. Experiment 1 established baseline differences between men and women; women made 12% more errors than did men. Experiment 2 found that exposure to a positive stereotype message enhanced women’s performance in comparison with that of another group of women who received neutral information. In Experiment 3, men who were exposed to the same stereotype message emphasizing a female advantage made more errors than did male controls, and the magnitude of error was similar to that for women from Experiment 1. The results suggest that the gender gap in mental rotation performance is partially caused by experiential factors, particularly those induced by sociocultural stereotypes.     

EPS Mid-Career Award 2004: brain mechanisms of attention

There are many varieties of "attention", to some extent separate yet working together to produce coherent perception, thought, and behaviour. Using data from human behaviour, functional neuroimaging, and single-cell recording in the behaving monkey, I consider different levels of attention and their basis in physiological mechanisms of biased competition. Beginning with visual attention, I suggest that processing is competitive in many brain systems that code visual input. Competition is biased towards stimuli that match task requirements and is integrated between systems coding different object properties. The result is flexible, object-based attentional selection. In the second part of the paper, I describe recent experiments on attentional competition within and between sensory modalities. Though competition is often modality specific, more global levels of interference are also easy to demonstrate. In the third part of the paper, I move to frontoparietal cortex and to a pattern of similar brain regions recruited by many different cognitive demands. This multiple-demand (MD) pattern, I suggest, reflects neurons with highly flexible response properties, adapting to represent the information and events of many different tasks. Biased competition in MD regions may play a central role in broad attentional capacity limits and attentional focusing. More generally, I suggest that biased competition is characteristic of many different cognitive domains and brain systems. Coherent "attention" develops as different systems converge to work on related cognitive content.     

Child well-being in an era of welfare reform: the sensitivity of transitions in development to policy change

This study examined the age-specific pattern of effects of welfare policies on child achievement. Drawing from 7 random-assignment welfare and antipoverty evaluations that provided more than 30,000 observations of children's achievement, this study found that times of developmental transition are the only periods sensitive to the changes in families brought about by these policies. More specifically, small positive effects of welfare and antipoverty policies were found for children making the transition into middle childhood, and small negative effects of these same policies were found for children making the transition out of middle childhood and into early adolescence. Effects were robust across various program groupings and could not be attributed to family characteristics that differ for children of different ages. This research informs the understanding of how changes in employment and income for low-income parents affect development across childhood.     

Relationship satisfaction and conflict over minor and major issues in romantic relationships

In this study the question of whether conflicts over minor issues and over major issues were equally strongly related to satisfaction in romantic relationships was examined. Sixty-four women and 29 men completed the Hendrick (1988) Relationship Assessment Scale for their current main romantic relationship and a 12-item conflict scale (Cramer, 2000b) for minor and major issues. All the relationships were heterosexual. Satisfaction was significantly and equally negatively correlated with conflict over minor and major issues, suggesting that whether an issue is of major or minor importance does not affect satisfaction or dissatisfaction in a romantic relationship. Thus, assessing conflict over major issues may be unnecessary in predicting relationship satisfaction. Conflict over minor and major issues was significantly and positively correlated even when satisfaction was controlled, indicating consistency in conflict resolution.     

Assessment of fine motor skill in musicians and nonmusicians: differences in timing versus sequence accuracy in a bimanual fingering task

While professional musicians are generally considered to possess better control of finger movements than nonmusicians, relatively few reports have experimentally addressed the nature of this discrepancy in fine motor skills. For example, it is unknown whether musicians perform with greater skill than control subjects in all aspects of different types of fine motor activities. More specifically, it is not known whether musicians perform better than control subjects on a fine motor task that is similar, but not identical, to the playing of their primary instrument. The purpose of this study was to examine the accuracy of finger placement and accuracy of timing in professional musicians and nonmusicians using a simple, rhythmical, bilateral fingering pattern and the technology that allowed separate assessment of these two parameters. Professional musicians (other than pianists) and nonmusicians were given identical, detailed and explicit instructions but not allowed physically to practice the finger pattern. After verbally repeating the correct pattern for the investigator, subjects performed the task on an electric keyboard with both hands simultaneously. Each subject's performance was then converted to a numerical score. While musicians clearly demonstrated better accuracy in timing, no significant difference was found between the groups in their finger placement scores. These findings were not correlated with subjects' age, sex, limb dominance, or primary instrument (for the professional musicians). This study indicates that professional musicians perform better in timing accuracy but not spatial accuracy while executing a simple, novel, bimanual motor sequence.