Induction when rats lick for 1% liquid-sucrose reinforcement

Previous research reported that rats responding for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement is upcoming will decrease their response rate (contrast) if licking is the dependent measure and increase their response rate (induction) if pressing a lever is the dependent measure. The present study investigated whether induction could be observed when licking served as the dependent measure and whether induction in lever pressing and contrast in licking behaviour could be concurrently observed. Experiment 1 found induction when rats licked to earn the rewards but consumed them at a location separate from the spout licked to earn them. Experiment 2 also found induction when rats earned (and consumed) rewards by licking the same spout throughout the session. Experiment 3 separately measured instrumental lever pressing for sucrose rewards and licking the sucrose during the reward period. We found that both measures increased for 1% sucrose when 32% sucrose reinforcement was upcoming. The present results indicate that the type of response is not the sole determinant of whether contrast or induction is observed. Rather, they suggest that other procedural details, such as the location of reinforcer delivery, influence which effect is observed. The results also indicate that associative processes underlie the appearance of induction in responding for 1% sucrose.     

Freedom in responsibility: a response.

This paper is a critical response to Elisabeth Gr?b-Schmidt's article "Freedom in responsibility: On the relevance of 'sin' as hermeneutic guiding principle in bioethical decision making." Gr?b-Schmidt's chief contention is that ethics begins with anthropology, and that moral responsibility is thereby grounded within a set of given limits. Freedom is distorted into sin when these limits are transgressed. My principal complaint is that her account of the relationship between freedom and sin is grounded in a tragic ontology. Alternatively, I contend that anthropology is grounded in Christology in which freedom is a gift of the Spirit. Consequently, sin is not so much tragic as it marks a refusal of humans to accept their divine election. The issues of human cloning and embryonic stem-cell research are used to exemplify what difference these respective differences might make in a process of moral deliberation.     

Novel stimuli are negative stimuli: evidence that negative affect is reduced in the mere exposure effect

Repeated exposure of a nonreinforced stimulus results in an increased preference for that stimulus, the mere exposure effect. The present study repeatedly presented positive, negative, and neutrally affective faces to 48 participants while they made judgments about the emotional expression. Participants then rated the likeability of novel neutrally expressive faces and some of these previously presented faces, this time in their neutral expression. Faces originally presented as happy were rated as the most likeable, followed by faces originally presented as neutral. Negative and novel faces were not rated significantly differently from each other. These findings support the notion that the increase in preference towards repeatedly presented stimuli is the result of the reduction in negative affect, consistent with the modified two-factor uncertainty-reduction model and classical conditioning model of the mere exposure effect.     

Lateral biases in assumptions of lighting position

People presume that the light source in pictures comes from above, and there is some evidence that this phenomenon also demonstrates lateral biases. When investigators present multiple ambiguous stimuli or visually complex objects, people assume that the source of light is from above, and to the left. However, when single relatively simple stimuli are presented, this lateral bias is not readily observed. To investigate whether lateral bias is dependent on the number of stimuli presented, the present experiment employs a within-subjects design to present single spheres or pairs of spheres. Contrary to our expectations, leftward biases were exhibited in both the single-sphere condition and the paired-spheres condition. Single spheres that were lit from the left were more likely to be judged as convex than comparable spheres lit from the right. Similarly, when pairs of laterally lit spheres were presented and participants were asked to judge which sphere appeared to be more convex, participants chose spheres lit from the left regardless of the angle of illumination. Collectively, these results suggest that there are lateral biases in assumptions of illumination position and that these biases do not depend on the number of stimuli being perceived at any given time.     

Substance versus style: a new look at social desirability in motivating contexts

Although there is an emerging consensus that social desirability does not meaningfully affect criterion-related validity, several researchers have reaffirmed the argument that social desirability degrades the construct validity of personality measures. Yet, most research demonstrating the adverse consequences of faking for construct validity uses a fake-good instruction set. The consequence of such a manipulation is to exacerbate the effects of response distortion beyond what would be expected under realistic circumstances (e.g., an applicant setting). The research reported in this article was designed to assess these issues by using real-world contexts not influenced by artificial instructions. Results suggest that response distortion has little impact on the construct validity of personality measures used in selection contexts.     

An examination of interrater reliability for scoring the Rorschach Comprehensive System in eight data sets

In this article, we describe interrater reliability for the Comprehensive System (CS; Exner. 1993) in 8 relatively large samples, including (a) students, (b) experienced re- searchers, (c) clinicians, (d) clinicians and then researchers, (e) a composite clinical sample (i.e., a to d), and 3 samples in which randomly generated erroneous scores were substituted for (f) 10%, (g) 20%, or (h) 30% of the original responses. Across samples, 133 to 143 statistically stable CS scores had excellent reliability, with median intraclass correlations of.85, .96, .97, .95, .93, .95, .89, and .82, respectively. We also demonstrate reliability findings from this study closely match the results derived from a synthesis of prior research, CS summary scores are more reliable than scores assigned to individual responses, small samples are more likely to generate unstable and lower reliability estimates, and Meyer's (1997a) procedures for estimating response segment reliability were accurate. The CS can be scored reliably, but because scoring is the result of coder skills clinicians must conscientiously monitor their accuracy.     

Influences of preclinical dementia and impending death on the magnitude of age-related cognitive deficits

The authors examined the influence of preclinical dementia and impending death on the cross-sectional relationship between age and performance in tasks assessing episodic memory, visuospatial skill, and verbal fluency. Increasing age was associated with a general decrease in cognitive performance. In addition, those who were to be diagnosed with dementia or had died by a 3-year follow-up, were older, and performed at a lower level than the remaining sample across all cognitive tasks at baseline. Nevertheless, removal of the preclinical dementia and impending death groups from the original sample affected the cross-sectional age-cognition relations relatively little. This pattern of findings suggests that the biological aging process exerts negative influences on cognitive functioning beyond those resulting from disease and mortality.     

Aged rats are impaired on an attentional set-shifting task sensitive to medial frontal cortex damage in young rats

Normal aging is associated with disruption of neural systems that subserve different aspects of cognitive function, particularly in the hippocampus and frontal cortex. Abnormalities in hippocampal function have been well investigated in rodent models of aging, but studies of frontal cortex function in aged rodents are few. We tested young (4–5 mo old) and aged (27–28 mo old) male Long-Evans rats on an attentional set-shifting task modified slightly from previous publication. After training on two problems in which the reward was consistently associated with the same stimulus dimension, and a reversal of one problem, a new problem was presented in which the reward was consistently associated with the previously irrelevant stimulus dimension (extradimensional shift [EDS]). Aged rats as a group were significantly impaired on the EDS, although some individual aged rats performed as well as young rats on this phase. In addition, some aged rats were impaired on the reversal, although a group effect did not reach significance in this phase. Impairment in neither reversal nor EDS was associated with impairments in spatial learning in the Morris water maze. Young rats with neurotoxic lesions of medial frontal cortex are also selectively impaired on the EDS. These results indicate that normal aging in rats is associated with impaired medial frontal cortex function. Furthermore, age-related declines in frontal cortex function are independent of those in hippocampal function. These results provide a possible basis for correlating age-related changes in neurobiological markers in frontal cortex with cognitive decline.     

Is smoking automatic? Demands of smoking behavior on attentional resources

The role of attention in the production of smoking behavior was investigated. Experienced and novice smokers were asked to perform a reaction time (RT) task under 4 conditions: while smoking (smoking), while mimicking all aspects of smoking except inhaling (pseudosmoking), while simply holding a cigarette (holding), and while not smoking (baseline). Experienced smokers' RTs increased during the pseudosmoking and holding conditions compared with baseline but did not differ between the smoking and baseline conditions, suggesting that attentional resources were not required for typical smoking behavior but were required to alter or inhibit smoking behavior. Novice smokers' RTs were slower during both the smoking and pseudosmoking conditions but not the holding condition, suggesting that novice smokers require the use of resources to smoke. Experiment 2 demonstrated that the differences in RT across conditions could not be explained by differences in urges.     

Sources of Heterogeneity in Schizophrenia: The Role of Neuropsychological Functioning

Although schizophrenia is often characterized as a heterogeneous disorder, efforts to validate stable and meaningful subtypes have met with limited success. Thus, the issue of whether schizophrenia reflects a continuum of severity or a number of discrete subtypes remains controversial. This review evaluates efforts to establish subtypes based upon a model that includes causes, characteristics, and course and outcomes of heterogeneity. Emphasis is placed on empirical classification studies utilizing cognitive tests or symptom rating scales, sometimes in conjunction with neuroimaging procedures. Results of recent cluster analytic studies are reviewed that produced evidence of four or five clusters, varying in level and pattern of performance. Although this research typically generated meaningful subtypes, it was often the case that there was little correspondence between subtyping systems based upon cognitive function and those based upon symptom profile. It was concluded that there may be different mechanisms for producing cognitive and symptomatic heterogeneity, and that diversity in presentations of schizophrenia reflects a combination of continuities in severity of the disorder with a number of meaningful and stable subtypes.