Inhibition and working memory: effect of acute sleep deprivation on a random letter generation task]

The literature contains inconsistent data on the effects of acute sleep deprivation on the superior cognitive functions. The primary purpose of this study is to determine the effectiveness of inhibition, one of the functions of the working memory executive centre (EC), over an extended, 36-hour waking period. Inhibition is a cognitive mechanism whereby individuals ignore non-relevant information recorded in their working memory. We also tested the effects of a 36-hour period of acute sleep deprivation on simple reaction time. Twelve young, healthy volunteers (M = 21.5 years, sigma = 2.3) performed a random generation task involving letters and a simple reaction time psychomotor test over four sessions held at 10-hour intervals. Each participant was assigned a "constant routine." Participants were kept awake in a prone position within a room whose environment was held strictly constant (light, noise, temperature, meals, etc.). This control procedure provided assurance that any variation in participant performance was solely caused by sleep deprivation. The random generation task, nearly two minutes in length, consisted in verbally producing a sequence of 100 letters in a random fashion (i.e. by inhibiting, for example, alphabetical order) and by keeping to a set rhythm. Our assumption was that capacity for inhibition diminished as the number of hours of sleep deprivation increased. The simple reaction test, 10 minutes in length, involved pressing a button as swiftly as possible to cause a black square to disappear from a screen. In this case our assumption was that acute sleep deprivation alters simple reaction time. Analysis of variance (ANOVA) through repeated measures using the "sessions" factor as an intra-subject variable showed no significant changes in randomization indices of the random generation task, contrary to analysis of average simple reaction times. Participants' reaction times deteriorated over the first two minutes of the test during the night they were deprived of sleep. It would seem that the contradictory results of previous studies of the effects of acute sleep deprivation on the inhibition function would be due to errors in factor identification. In conclusion, the inhibition function, as measured during the performance of a brief task, seems to remain intact during an extended, 36-hour waking period. Simple reaction time assessed by means of a brief psychomotor test is affected during a night of sleep deprivation. The working-memory inhibition executive function shows greater resistance to acute sleep deprivation than does psychomotor reaction time for the performance of short tasks.     

Ethnic identity, self-esteem, and ethnocentrism: a study of social identity versus multicultural theory of development

Social identity theory (SIT) proposes that the more strongly individuals identify with their group, the less favorable attitudes they hold toward dissimilar groups. In contrast, multicultural theory proposes that affirmation toward one's group--particularly with respect to ethnicity--should correspond with higher levels of acceptance toward dissimilar groups. These competing theories were examined with 486 non-Hispanic White, African American, and Hispanic/Latino university students to determine if support would be found for either theory. Consistent with SIT, levels of ethnic identity correlated significantly with levels of ethnocentrism for Whites and Hispanics but not for African Americans. African Americans obtained significantly higher ethnic identity and self-esteem scores than the other 2 groups. Implications of the findings are discussed.     

How conscious experience and working memory interact

Active components of classical working memory are conscious, but traditional theory does not account for this fact. Global Workspace theory suggests that consciousness is needed to recruit unconscious specialized networks that carry out detailed working memory functions. The IDA model provides a fine-grained analysis of this process, specifically of two classical working-memory tasks, verbal rehearsal and the utilization of a visual image. In the process, new light is shed on the interactions between conscious and unconscious aspects of working memory.     

Perception of /r/ and /l/ in a stop cluster: evidence of cross-modal context effects

Experiments were conducted investigating unimodal and cross-modal phonetic context effects on /r/ and /l/ identifications to test a hypothesis that context effects arise in early auditory speech processing. Experiment 1 demonstrated an influence of a preceding bilabial stop consonant on the acoustic realization of /r/ and /l/ produced within the stop clusters /ibri/ and /ibli/. In Experiment 2, members of an acoustic /iri/ to /ili/ continuum were paired with an acoustic /ibi/. These dichotic tokens were associated with an increase in "l" identification relative to the /iri/ to /ili/ continuum. In Experiment 3, the /iri/ to /ili/ tokens were dubbed onto a video of a talker saying /ibi/. This condition was associated with a reliable perceptual shift relative to an auditory-only condition in which the /iri/ to /ili/ tokens were presented by themselves, ruling out an account of these context effects as arising during early auditory processing.     

Morally Relevant Features

This article summarizes the account of morality presented in Morality: Its Nature and Justification (Oxford, 1998), with emphasis on that aspect of morality that deals with justifying violations of the moral rules. Such justification requires a two-step procedure; the first is describing the situation using only morally relevant features. I list these features, noting how diverse they are, and describe their characteristics. The second step is estimating the consequences of publicly allowing a violation with the same morally relevant features, that is, allowing a violation when everyone knows that it is allowed to violate the rule in the same circumstances, and comparing this to the estimated consequences of not publicly allowing that kind of violation. I then explain why fully informed, impartial rational persons can sometimes disagree about whether a violation should be publicly allowed and note that such weakly justified violations are the controversial cases.     

How young children spend their time: television and other activities.

Time-use diaries were collected over a 3-year period for 2 cohorts of 2- and 4-year-old children. TV viewing declined with age. Time spent in reading and educational activities increased with age on weekdays but declined on weekends. Time-use patterns were sex-stereotyped, and sex differences increased with age. As individuals' time in educational activities, social interaction, and video games increased, their time watching entertainment TV declined, but time spent playing covaried positively with entertainment TV. Educational TV viewing was not related to time spent in non-TV activities. Maternal education and home environment quality predicted frequent viewing of educational TV programs and infrequent viewing of entertainment TV. The results do not support a simple displacement hypothesis; the relations of TV viewing to other activities depend on the program content, the nature of the competing activity, and the environmental context.     

Conduct Disorder in Girls: A Review of the Literature

The study of Conduct Disorder (CD) has primarily been limited to boys. The lack of research resulted from a premise that CD in girls was rare. However, CD in girls is a relatively common psychiatric diagnosis, and appears to be associated with several serious outcomes, such as Antisocial Personality Disorder and early pregnancy. Understanding gender differences in the course and severity of CD may lead to important information about etiology. Empirical studies on precursors, developmental course, risk factors and treatment for CD in girls are reviewed, while highlighting similarities and differences between girls and boys. Generally, CD symptoms in girls are stable. Precursors to CD in girls probably include Oppositional Defiant Disorder and temperamental factors, but also may include certain negative cognitions. What distinguishes CD in girls is the high risk they have to develop comorbid conditions, especially internalizing disorders. Risk factors for CD in girls partly overlap with those known for boys, but some factors appear to be highly salient for girls. Finally, there may be some significant effects of gender on treatment efficacy. Implications of these findings for future etiologic research are discussed.     

Keeping Up with the Cloneses -- Issues in Human Cloning

The advent of cloning animals has created a maelstrom of social concern about the ethical issues associated with the possibility of cloning humans. When the ethical concerns are clearly examined, however, many of them turn out to be less matters of rational ethics than knee-jerk emotion, religious bias, or fear of that which is not understood. Three categories of real and spurious ethical concerns are presented and discussed: 1) that cloning is intrinsically wrong, 2) that cloning must lead to bad consequences, and 3) that cloning harms the organism generated. The need for a rational ethical framework for discussing biotechnological advances is presented and defended.     

In these pages . . .

The American Journal of Psychoanalysis -