Facilitation of large ratio performance by use of conditioned reinforcement

Fixed ratio performance was examined in the chimpanzee under two alternating conditions. In one, conditioned reinforcement followed successive fractions of the total ratio, and in the other it was omitted. Shorter pauses and working times, and the development of a strong preference resulted for the condition affording conditioned reinforcement.     

Concurrent measurement of heart rate and instrumental avoidance behavior in the Rhesus monkey

A graphical method has been developed for the concurrent recording of heart beats and lever responses during behavioral experiments. The EKG signal fed into any DC amplifier goes to a fixed level trigger circuit and relay driver with its own power supply. The signal from this drives any standard cumulative recorder. Lever response rates are recorded concurrently on an additional cumulative recorder using the same paper speed.     

Positive and negative reinforcement effects on behavior in a three-person microsociety

Three-person groups, either of males or of females, resided for 6 to 12 days in a continuously programmed environment. Subjects followed a behavioral program that determined the sequential and contingent relations within an inventory of activities. The program consisted of positive reinforcement days and avoidance days. During a positive reinforcement day, each work unit completed by a subject incremented a group account. The account was divided evenly among the three participants at the conclusion of the study. During a negative reinforcement day, no money was earned, and the group was assigned work unit criterion that, if completed, prevented a reduction in accumulated earnings. During negative reinforcement days, subjects made aggressive verbal responses, which differed in magnitude among the four groups. These differences were evident in several distinct behavioral measures. Performances on components of the work unit were not demonstrably affected by the reinforcement schedules in effect, although during the avoidance condition one subject stopped working and another subject's productivity declined.     

Frontal brain asymmetry in depression with comorbid anxiety: a neuropsychological investigation

The approach-withdrawal model posits that depression and anxiety are associated with a relative right asymmetry in frontal brain activity. Most studies have tested this model using measures of cortical brain activity such as electroencephalography. However, neuropsychological tasks that differentially use left versus right frontal cortical regions can also be used to test hypotheses from the model. In two independent samples (Study 1 and 2), the present study investigated the performance of currently depressed individuals with or without a comorbid anxiety disorder and healthy controls on neuropsychological tasks tapping primarily left (verbal fluency) or right (design fluency) frontal brain regions. Across both samples, results indicated that comorbid participants performed more poorly than depressed only and control participants on design fluency, while all groups showed equivalent performance on verbal fluency. Moreover, comorbid participants showed "asymmetrical" performance on these two tasks (i.e., poorer design [right frontal] relative to verbal [left frontal] fluency), whereas depressed only and control participants showed approximately symmetrical profiles of performance. Results from these two samples suggest an abnormal frontal asymmetry in neurocognitive performance driven primarily by right frontal dysfunction among anxious-depressed individuals and highlight the importance of considering comorbid anxiety when examining frontal brain functioning in depression.     

Dual-tasking alleviated sleep deprivation disruption in visuomotor tracking: an fMRI study

Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a target and non-matches were non-targets. Tracking error means were binned time-locked to stimulus onset of the detection task in order to observe changes associated with dual-responding by comparing the error during targets and non-targets. Similar comparison was made with fMRI data. Our result showed that despite a significant increase in the overall tracking error post SD, from 20 pixels pre SD to 45 pixels post SD, error decreased to a minimum of about 25 pixels 0-6s after dual-response. Despite an overall reduced activation post SD, greater activation difference between targets and non-targets was found post SD in task-related regions, such as the left cerebellum, the left somatosensory cortex, the left extrastriate cortex, bilateral precuneus, the left middle frontal gyrus, and the left motor cortex. Our results suggest that dual-response helps to alleviate performance impairment usually associated with SD. The duration of the alleviation effect was on the order of seconds after dual-responding.     

Exploring Societal and Ethical Views of Nanotechnology REUs

Little previous research has examined attitudes about societal and ethical issues (SEI) among interns participating in research experience for undergraduate programs (REUs) in nanotechnology, thus neglecting an important population for understanding the burgeoning views of the next generation of nanotechnology researchers. This study surveyed a sample of interns (N?=?85) participating in the National Nanotechnology Infrastructure Network’s (NNIN) REU program during the summer of 2012. Our questions focused on interns’ experiences with education on ethical issues, as well as their attribution of responsibility for considering ethical issues, motivations to talk about ethical issues, and comfort level of discussing ethical issues with faculty, mentors, lab staff, and other REU students. Among key findings was that lab culture related to the extent to which REU interns felt comfortable discussing ethical issues. In addition, those who reported more discussions about ethical issues with their mentors were more likely to consider themselves as responsible for considering ethical issues. We conclude with recommendations and future research directions.     

Sociocultural pressures and adolescent eating in the absence of hunger

Parental feeding practices and sociocultural pressures theoretically influence eating behavior. Yet, whether these factors relate to eating in the absence of hunger (EAH) is unknown. We assessed if sociocultural pressures were associated with EAH among 90 adolescents (M_age = 15.27, SD = 1.39; 48% female). Parents completed the Child Feeding Questionnaire. Adolescents completed the Perceived Sociocultural Pressures Scale, Sociocultural Attitudes Towards Appearance Questionnaire-3, and Multidimensional Body Self-Relations Questionnaire-Appearance Scales. On two occasions, EAH was assessed as snack food intake after adolescents ate to satiety. Controlling for body composition and demographics, parental restriction and family pressure to be thin were associated with greater EAH. Media pressure was related to more EAH in girls. Appearance orientation and preoccupation with becoming overweight mediated links between sociocultural pressures and EAH. Findings support the notion that sociocultural pressures and their links to body image may contribute to the course of disinhibited eating behaviors during adolescence.     

Does anxiety sensitivity correlate with startle habituation? An examination in two independent samples

Individuals with anxiety disorders have previously demonstrated abnormal habituation to aversiveness over time. As anxiety sensitivity (AS), or an individuals' propensity to fear of anxiety-related sensations, has been shown to be a risk factor for anxiety disorders (particularly panic disorder), the present study examined whether AS was also associated with abnormal habituation. This association was examined in two independent samples of undergraduates (N_total=178). Habituation was operationalised as the reduction in startle response to multiple startle probes presented over 2.5 minutes and three definitions of this reduction were employed. Results indicated that individuals with higher levels of AS evidenced deficits in startle habituation, but the strength of this relationship was somewhat dependent on the definition of startle habituation, with the most robust definition being an analysis of participants' individual slopes across all nine blinks. The present findings suggest that startle habituation is a key mechanism underlying AS, and may help elucidate the role this risk factor plays in the pathogenesis of anxiety disorders.