Dopamine D2 receptors mediate reversal learning in male C57BL/6J mice

Dopamine is critical for directing goal-oriented behavior. We investigated dopamine D₂ receptor involvement in reversal learning and reinforcement efficacy in mice lacking functional dopamine D₂ receptors and their heterozygous and wild-type littermates. Mice discriminated between two odors to receive a food reinforcer: One odor signaled a reinforcer (S⁺); the other odor signaled no reinforcer (S⁻). After mice learned the S⁺/S⁻ relationship, we inverted the reinforcement contingencies. The necessary number of trials to relearn the new reinforcement contingencies served as our index of reversal learning. Mice lacking functional dopamine D₂ receptors repeatedly failed to inhibit previously reinforced responses during reversal trials. In a separate experiment, mice responded for reinforcers on a progressive ratio schedule of reinforcement. Mice lacking functional dopamine D₂ receptors earned significantly fewer reinforcers than did heterozygous mice. Our results suggest that dopamine D₂ receptors regulate reversal learning and influence the reinforcing efficacy of natural rewards.     

Genetic modification and genetic determinism

In this article we examine four objections to the genetic modification of human beings: the freedom argument, the giftedness argument, the authenticity argument, and the uniqueness argument. We then demonstrate that each of these arguments against genetic modification assumes a strong version of genetic determinism. Since these strong deterministic assumptions are false, the arguments against genetic modification, which assume and depend upon these assumptions, are therefore unsound. Serious discussion of the morality of genetic modification, and the development of sound science policy, should be driven by arguments that address the actual consequences of genetic modification for individuals and society, not by ones propped up by false or misleading biological assumptions.     

Throughput: A simple performance index with desirable characteristics

Throughput is a corrected response rate measure giving the number of successes per unit of discretionary time. It is a simple but general index applicable to psychomotor, behavioral, and cognitive tasks in which response times are measured. This measure has several attractive features: (1) It allows comparisons to be made across various tasks in which speed and accuracy are meaningful and measurable, independently of temporal differences in hardware, software, and procedures; (2) under conditions in which both speed and accuracy decline (or improve), throughput will be a more sensitive index of performance than either alone will be; and (3) in those tasks in which the speed—accuracy trade-off phenomenon operates, throughput will tend to be relatively less variable than either component alone will be. The measure allows both behavioral and information-processing interpretations of data and may be useful as a simple composite index, a measure of effectiveness or of cognitive consistency in studies investigating performance degradation or enhancement.     

The swimsuit issue: Correlates of body image in a sample of 52,677 heterosexual adults

Past research on adults’ body image has typically used small convenience samples, limiting the ability to examine associations of personal characteristics to body satisfaction. This study of 52,677 heterosexual adults ages 18–65 examined associations of body satisfaction to age, height, gender, and body mass index (BMI). Age and height were mostly unrelated to body satisfaction. Consistent with an Objectification Theory perspective, fewer men than women reported being too heavy (41% versus 61%), rated their body as unattractive (11% versus 21%), or avoided wearing a swimsuit in public (16% versus 31%). Men felt better about their bodies than women across most of the weight span, although among underweight individuals, women felt better than men. Slender women (BMIs 14.5–22.49) were more satisfied than most other women (BMIs 22.5–40.5). Among men, underweight and obese men were least satisfied. These findings highlight gender differences in the association of weight to body satisfaction.     

Resistance to the impact of interruptions during multitasking by healthy adults and dysexecutive patients

Two experiments (one with healthy adult volunteers and the other with controls and dysexecutive patients) assessed the impact of interruptions on a novel test of multitasking. The test involved switching repeatedly between four tasks (block construction, bead threading, paper folding, alphabetical searching) over a 10 min period. In Experiment 1, there were four groups of 20 healthy participants. One group attempted multitasking with no interruption, a second group was interrupted early in the test, a third group late in the test and a fourth group was interrupted both early and late. Interruption involved carrying out a fifth, unexpected task for a period of 1 min before returning to the four main tasks. There was no difference in multitasking performance between the groups. In Experiment 2 the participants were seven dysexecutive patients and 14 age-matched controls. A repeated measures approach was employed to assess the impact of two interruptions (early and late) for both groups. Contrary to predictions, the patients as well as controls were resistant to the effects of interruptions, despite their clearly impaired multitasking performance. These results suggest that the ability to deal with interruptions may be separable from the ability to organise and execute multiple tasks within a limited time frame.     

Stages of change in anxiety: psychometric properties of the University of Rhode Island Change Assessment (URICA) scale

Readiness for change is increasingly cited as an important variable in the health behaviours literature, yet there remains a dearth of research related to this construct in mental health. This study examined the psychometric properties of the University of Rhode Island Change Assessment (URICA) scale in two samples. In Study 1 (n = 252), undergraduates completed the URICA and were administered measures of hopelessness, the consequences of worry, self-esteem, anxious symptomatology, and social desirability. The reliability and validity of the URICA were generally supported, although the goodness-of-fit with the intended subscales was only moderate. The Precontemplation, Contemplation and Maintenance subscales correlated as expected with ancillary measures, but the Action subscale did not. In Study 2 (n = 81), individuals with panic disorder were administered the URICA at initial assessment and following cognitive behavioural therapy. The URICA demonstrated excellent reliability, significantly predicted treatment retention and dropout, and showed modest utility for predicting treatment outcome. Confirmatory factor analysis, however, revealed an inadequate fit to the intended subscales. The implications of these findings are discussed and directions for future research highlighted.     

Studies of the vicarious traumatization of college students by the September 11th attacks: effects of proximity, exposure and connectedness

From mid-October 2001 through the end of November 2001, we collected fairly large sets of questionnaires from undergraduates at three public universities (Albany, NY, n = 507, Augusta, GA, n = 336, Fargo, ND, n = 526 ) to assess rate of acute stress disorder (ASD) and level of ASD symptoms following the September 11th attacks, rate of current posttraumatic stress disorder (PTSD) and level of PTSD symptoms, and current level of depressive symptoms resulting from the September 11th attacks. We also gathered information on exposure to media coverage of the attacks, connectedness to the World Trade Center (WTC) and personnel there, and degree of engagement in reparative acts such as giving blood, attending vigils. We found higher levels of ASD, ASD symptoms, PTSD and PTSD symptoms as a function of geographical proximity to New York City (and within the Albany site, proximity of students' homes) and gender. Exposure (hours of TV watched) was a predictor in some instances as was connectedness to WTC victims. ASD symptoms were the strongest predictor of subsequent PTSD symptoms. Path models accounted for over 60% of the variance in PTSD symptoms.