Conditioning of the aggressive behavior of pigeons by a fixed-interval schedule of reinforcement

Operant reinforcement of aggression was studied in food-deprived pigeons by delivering food for attacks against a target pigeon. The food was delivered according to a fixed-interval schedule and attack behavior was recorded automatically. Attack could be conditioned and extinguished, and the proportion of time spent in attack was a direct function of the frequency of reinforcement of the attack. The fixed-interval schedule produced an increasing rate of attack during the interval between food reinforcements. This positive curvature was an inverse function of the duration of the interval. The findings revealed that the duration and temporal patterning of the complex social behavior of attack can be influenced in a substantial and predictable manner by the schedule and frequency of operant reinforcement.     

Profile of problem children from a rural county in Indiana

In order to better identify and understand problems experienced by delinquent children and adolescents in a rural county in Indiana, in-the-trenches professionals working with these children were interviewed. Comparisons are drawn between observations of these professionals and existing research findings regarding Disruptive Behavior Disorders (i.e., ADHD, ODD, CD).     

Perceived calorie intake and state body-image satisfaction in women attempting weight loss: A preliminary investigation

State body-image satisfaction levels (BIS) can be predicted by appearance concerns, eating attitudes and body mass index (BMI). Determinants of state BIS and its variability were examined in women attempting weight loss. Little is known about contextual cues that influence state BIS; therefore the effect of eating on BIS was examined. Forty-six females attending a commercial weight loss group completed measures of shape and weight concerns, appearance beliefs and dietary restraint, followed by completion of a diary that assessed state BIS, mood and perceived calorie intake immediately following evening meals. Regression analysis indicated that after controlling for mood, state BIS was associated with higher BMI and dietary restraint. Greater variability in state BIS was associated with greater variability in perceived calorie intake. This relationship was fully mediated by greater variability in mood. The findings imply that state BIS warrants investigation as a process that may influence weight loss management.     

Case-Mixing Effects on Spelling Recognition: The Importance of Test Format

In a multiple-choice spelling recognition test, 56 university students were more accurate on more regular than irregular words, and on lower-case than mixed-case words, with the case mixing effect greater for irregular than regular words. In Experiment 2, the same words were presented singly in correct or incorrect spellings and distortion of word shape was achieved by case mixing (32 subjects) or by alternating the size of lower-case letters within a word (32 subjects). The main effects of regularity and distortion were replicated and the effect of distortion was greater for incorrect than correct stimuli, with correctly spelled words suffering a decrement in accuracy of less than 5 percentage points. Case mixing had a greater effect than size mixing on response latencies. In Experiment 3, with comparable test procedures, case mixing interacted with regularity in the subjects analysis for the multiple choice format, but not the single presentation format. This result indicates that comparisons based on visual configuration may be an artifact of multiple-choice tests.     

Care Orientation in the Teens as a Predictor of Young Adult Psychosocial Adjustment

The transition from adolescence to young adulthood is a watershed period in development that carries risk for poor psychosocial adjustment. It also carries potential for positive transitions into the caregiving roles and responsibilities of adult life. Research to date has predominantly focused on adolescent predictors of problematic rather than positive transitions; yet predictors of the latter hold equal (if not greater) promise for informing health promoting interventions. The purpose of this study was threefold: (1) to use Latent Profile Analysis (LPA) to define patterns of psychosocial adjustment and maladjustment in young adulthood (21-years of age); (2) to examine the unique role of adolescent prosocial behaviour (e.g., volunteering and civic engagement) in promoting adjustment and reducing maladjustment in young adulthood; and, (3) to examine whether protective developmental relationships are maintained after adjustment for other covariates including socio-economic background factors and personality characteristics. Data were drawn from the Victorian cohort of the International Youth Development Study (IYDS; N = 2407), a representative sample of students in Victoria, Australia. Students were assessed in Grade 9 (Mean age = 15-years) and followed up at age 21-years. LPA identified three psychosocial adjustment classes at age 21 defined as: (1) Adjusted (24.8 %); (2) Normative (63.9 %); and, (3) Maladjusted (11.3 %). Adolescent volunteering, belief in a moral order, family opportunities for prosocial behaviour, and commitment to school were associated with enhanced adjustment and reduced maladjustment in young adulthood. Findings highlight the potential benefit of interventions designed to enhance adolescent prosocial behaviours and care orientation in promoting healthy transitions into young adult life.     

Triggering social interactions: chimpanzees respond to imitation by a humanoid robot and request responses from it

Even the most rudimentary social cues may evoke affiliative responses in humans and promote social communication and cohesion. The present work tested whether such cues of an agent may also promote communicative interactions in a nonhuman primate species, by examining interaction-promoting behaviours in chimpanzees. Here, chimpanzees were tested during interactions with an interactive humanoid robot, which showed simple bodily movements and sent out calls. The results revealed that chimpanzees exhibited two types of interaction-promoting behaviours during relaxed or playful contexts. First, the chimpanzees showed prolonged active interest when they were imitated by the robot. Second, the subjects requested ‘social’ responses from the robot, i.e. by showing play invitations and offering toys or other objects. This study thus provides evidence that even rudimentary cues of a robotic agent may promote social interactions in chimpanzees, like in humans. Such simple and frequent social interactions most likely provided a foundation for sophisticated forms of affiliative communication to emerge.     

Is pressure stressful? The impact of pressure on the stress response and category learning

We examined the basic question of whether pressure is stressful. We proposed that when examining the role of stress or pressure in cognitive performance, it is important to consider the type of pressure, the stress response, and the aspect of cognition assessed. In Experiment 1, outcome pressure was not experienced as stressful but did lead to impaired performance on a rule-based (RB) category-learning task, but not on a more procedural information-integration (II) task. In Experiment 2, the addition of monitoring pressure resulted in a modest stress response to combined pressure and impairment on both tasks. Across experiments, higher stress appraisals were associated with decreased performance on the RB, but not on the II, task. In turn, higher stress reactivity (i.e., heart rate) was associated with enhanced performance on the II, but not on the RB, task. This work represents an initial step toward integrating the stress cognition and pressure cognition literatures and suggests that integrating these fields may require consideration of the type of pressure, the stress response, and the cognitive system mediating performance.     

Language statistics explain the spatial–numerical association of response codes

The spatial–numerical association of response codes (SNARC) has shown that parity judgments with participants’ left hands yield faster response times (RTs) for smaller numbers than for larger numbers, with the opposite result for right-hand responses. These findings have been explained by participants perceptually simulating magnitude on a mental number line. In three RT experiments, we showed that the SNARC effect can also be explained by language statistics. Participants made parity judgments of number words (Exp. 1) and Arabic numerals (Exp. 2). Linguistic frequencies of the number words and numbers mirrored the SNARC effect, explaining aspects of processing that a perceptual simulation account could not. In Experiment 3, we investigated whether high- and low-frequency nonnumerical words would also elicit a SNARC-like effect. Again, RTs were faster for high-frequency words for left-hand responses, with the opposite result for right-hand responses. These results demonstrate that what has only been attributed to perceptual simulation should also be attributed to language statistics.