Aldactazide-induced consummatory and operant responding to sodium by rats.

The effects of intraperitoneal injections of Aldactazide-A on rats' consumption of water and saline solution (.51M NaCl) were tested in two experiments. During the treatment sessions, the rats showed a substantial increase in saline consumption and in lever pressing to a cue light to obtain the saline, as compared with their negligible intake before the injections and after the injections had been discontinued. The results indicate that both the drinkometer and operantbox measures are sensitive to the natroexigenic effects of Aldactazide.     

Chimpanzee responding during matching to sample: control by exclusion

Three chimpanzees performed a computerized matching-to-sample task in which samples were photographs of items and comparison stimuli were geometric symbols called lexigrams. In Experiment 1, samples were either defined (i.e., they represented items that were associated already with a specific lexigram label by the chimpanzees) or undefined (i.e., they did not have an already learned association with a specific lexigram). On each trial, the foil (incorrect) comparison could be either a defined or an undefined lexigram. All 3 chimpanzees selected the correct comparison for undefined samples at a level significantly better than chance only when the foil comparison was defined. In Experiment 2, three comparisons were presented on each trial, and in Experiment 3, four comparisons were presented on each trial. For Experiments 2 and 3, the foil comparisons consisted of either defined or undefined comparisons or a mixture of both. For these two experiments, when the chimpanzees were presented with an undefined sample, they typically made selections of only undefined comparisons. These data indicate that the chimpanzees responded through use of exclusion. A final experiment, however, indicated that, despite the use of exclusion to complete trials with undefined samples correctly, the chimpanzees did not learn new associations between undefined samples and comparisons.     

Loss of control over eating reflects eating disturbances and general psychopathology

This study examined the clinical significance of the loss of control over eating as a key component of eating disorders. It investigated the association of eating-related psychopathology and general psychopathology with objective bulimic episodes (OBEs; experiencing a loss of control while consuming large amounts of food) and subjective bulimic episodes (SBEs; experiencing a loss of control while consuming small/moderate amounts). A community sample of 81 women with a range of disordered eating was recruited: binge-eating disorder, bulimia nervosa, subclinical eating disturbances, or no eating disorders. They were interviewed using the Eating Disorder Examination and completed measures of eating-related and general psychopathology. Both OBE and SBE frequencies correlated significantly with measures of eating-related and general psychopathology, and no significant differences were found between the magnitudes of the correlations with either binge episode type. SBE frequency significantly and independently predicted global eating disorder psychopathology. The loss of control over eating, without consuming large amounts of food, was as closely associated with specific eating disorder psychopathology and general mental health as were traditionally defined OBEs. SBEs may be an important target of treatment and should be considered for future diagnostic classifications of eating disorders.     

Anxiety sensitivity and perceived control over anxiety-related events: evaluating the singular and interactive effects in the prediction of anxious and fearful responding to bodily sensations

The present investigation examined the singular and interactive effects of anxiety sensitivity and perceived control over anxiety-related events in the prediction of panic symptoms using a CO(2)-enriched air biological challenge. Two hundred and twenty-nine adult participants (M(age)=21.02, SD=7.55, 124 females) were recruited from the greater Burlington, Vermont community. Results indicated that pre-challenge anxiety sensitivity, but not perceived control over anxiety-related events, significantly predicted post-challenge panic attack symptoms, anxiety focused on bodily sensations, and, interest in returning for another challenge (behavioral avoidance). In regard to physiological findings, anxiety sensitivity was significantly related to skin conductance level whereas perceived control over anxiety-related events was related to respiration rate. Neither anxiety sensitivity nor perceived control over anxiety-related events was related to heart rate. There also were no interactive effects between anxiety sensitivity and perceived control over anxiety-related events for any of the studied dependent variables. Results are discussed in relation to multi-risk factor models of cognitive vulnerability for panic psychopathology.     

Cooperative responding in rats maintained by fixed‐ and variable‐ratio schedules

The present study investigated the effects of fixed‐ratio (FR) and variable‐ratio (VR) reinforcement schedules on patterns of cooperative responding in pairs of rats. Experiment 1 arranged FR 1, FR 10, and VR 10 schedules to establish cooperative responding (water delivery depended on the joint responding of two rats). Cooperative response rates and proportions were higher under intermittent schedules than under continuous reinforcement. The FR 10 schedule generated a break‐and‐run pattern, whereas the VR 10 schedule generated a relatively high and constant rate pattern. Experiment 2 evaluated the effects of parametric manipulations of FR and VR schedules on cooperative responding. Rates and proportions of cooperative responding generally increased between ratio sizes of 1 and 5 but showed no consistent trend as the ratio increased from 5 to 10. Experiment 3 contrasted cooperative responding between an FR6 schedule and a yoked control schedule. Coordinated behavior occurred at a higher rate under the former schedule. The present study showed that external consequences and the schedules under which the delivery of these consequences are based, select patterns of coordinated behavior.     

Evidence that resident male albino rats are not immune to attacks by conspecific intruders

Offensive behaviors were exhibited by adult intact- and castrated-male Sprague-Dawley rats introduced into established home-cages of male conspecifics. Implications of this result for Adams' [1976] model of intraspecific fighting are presented.     

Memories and anticipations control responding by rats (<Emphasis Type="Italic">Rattus norvegicus</Emphasis>) in a Pavlovian procedure

In Experiment 1 each rat received two different fixed series of three trials each. The unconditioned stimulus occurred on Trial 1 of one series and on Trial 3 of the other series, all other trials being nonreinforced. Previous Pavlovian investigations have shown that rats can remember the immediately prior reward outcome and anticipate the immediately subsequent reward outcome. Experiment 1 demonstrated that rats could remember and anticipate even more remote reward outcomes. In Experiment 2 two groups received a series of two nonrewarded trials followed by a rewarded trial. It was demonstrated that a change in the conditioned stimulus (CS) from Trial 2 to Trial 3, which occurred in one group, produced weaker responding than in the other group that did not experience such CS change. On the basis of these findings it was suggested that the rats organized the trials of a series into a unit or chunk. This was concluded for two reasons. First, remembering and anticipating remote reward outcomes strongly suggests that responding is being controlled by events extending beyond the current trial. Secondly, the experimental manipulations employed in the Pavlovian situation here are similar to those used in prior human learning and animal instrumental learning investigations concerned with chunking. Thus, it would appear that chunking is a ubiquitous phenomenon appearing in human serial learning (e.g., Bower and Winzenz 1969; Crowder 1976), in animal instrumental learning (e.g., Capaldi 1992; Hulse and Dorsky 1977; Terrace 1987), and now in Pavlovian learning.     

Spatial memory over long retention intervals: nonmemorial factors are not necessary for accurate performance on the radial-arm maze by rats

A. Markowska, O. Buresová, and J. Bures (1983, Behavioral and Neural Biology, 38, 97-112) argued that the apparent persistence of accurate spatial working memory over delays of several hours arises from the formation of response strategies and the use of olfactory stimuli that develop with extended training at long delays. To test this explanation rats with extensive prior training at long delays were forced to enter the first four arms in a random order. On test days, the maze was rotated 180 degrees during the 2-h retention interval to determine whether the rats were using intramaze or extramaze (i.e., spatial) cues to guide their choices. On both rotation and control days, postdelay choices were spatially guided, averaging over 90% correct. Accurate spatial working memory at long delays is a reproducible phenomenon and does not appear to result from nonmemorial artifacts.     

Children's control over attention to phonological and semantic properties of words

A study is reported in which children from 5 to 9 years old were examined as they gained awareness and control over the phonological and semantic properties of isolated words. Children were asked to match a stimulus words on the basis of either its sound or its meaning under conditions that varied in their support for the correct answer. The results are presented as discriminability data, indicating the child's ability to distinguish these properties under the different experimental conditions. Although all the children could select either of these properties in a simple control condition, adding various levels of distraction interrupted their ability to attend to the requested feature. In the age range examined, the youngest children were unable to attend selectively to either feature, older children adopted a default or bias to phonological properties, and only the oldest children were able to attend to meaning as well as sound. Even for the oldest children, however, performance was far from perfect.     

Adding fear to conflict: A general purpose cognitive control network is modulated by trait anxiety

Studies of cognitive control show that the dorsal anterior cingulate cortex (dACC) and dorsolateral prefrontal cortex are involved in the detection and resolution of cognitive conflict. However, the neural and behavioral mechanisms underlying emotional interference effects are less consistent. We used fMRI during emotional and nonemotional versions of a facial Stroop task to investigate the effects of emotional stimuli on cognitive control. In the full group there was limited evidence that different prefrontal circuits manage conflict arising from emotional and nonemotional distractors. However, individual differences in trait anxiety affected both behavioral performance and neural activity during the emotional task. Relative to low-anxiety (LA) subjects, high-anxiety (HA) subjects showed greater amygdala activity to task-relevant emotional information and impaired performance and greater conflict-related activity in the dACC when emotional content was task-irrelevant. Only LA subjects activated rostral ACC during the emotional task. This is consistent with cognitive models of individual differences that hypothesize deficient control of task-irrelevant emotional information in HA subjects. Additional behavioral and fMRI results from this study may be downloaded from http://cabn.psychonomic-journals .org/content/supplemental.     

Exploring how symptoms of attention-deficit/hyperactivity disorder are related to reading and mathematics performance: general genes, general environments

Children with attention-deficit/hyperactivity disorder (ADHD) tend to perform more poorly on tests of reading and mathematical performance than their typical peers. Quantitative genetic analyses allow for a better understanding of the etiology of ADHD and reading and mathematics outcomes, by examining their common and unique genetic and environmental influences. Analyses were conducted on a sample 271 pairs of 10-year-old monozygotic and dizygotic twins drawn from the Western Reserve Reading and Mathematics Project. In general, the results suggested that the associations among ADHD symptoms, reading outcomes, and math outcomes were influenced by both general genetic and general shared-environment factors. The analyses also suggested significant independent genetic effects for ADHD symptoms. The results imply that differing etiological factors underlie the relationships among ADHD and reading and mathematics performance. It appears that both genetic and common family or school environments link ADHD with academic performance.     

Empathizing and systemizing are differentially related to dimensions of autistic traits in the general population

Background/Objective:

Empathizing-Systemizing Theory suggests that low empathizing and high systemizing are linked to autistic traits in the general population. Evidence from autistic individuals is convincing, but more research in the normal population is needed. Method: We conducted two surveys (N = 3,345) investigating the relationships between empathizing, systemizing and autistic traits in the general population, using a large variety of self-report instruments and direct performance tests. Results: Strong connections between autistic symptoms, empathizing, and systemizing were found using commonly used measures (Autism Quotient, Systemizing Quotient and Empathizing Quotient). Other measures on empathizing and systemizing found the connections that E-S-theory predicts, but the correlations were a lot more modest. Weak empathizing was related to autism's social difficulties, while systemizing was linked to non-social aspects of autism. Conclusions: The present results support the main tenets of empathizing-systemizing theory, but suggest that earlier findings might be inflated due to overlapping items in the most common assessment instruments.     

Running and responding reinforced by the opportunity to run: effect of reinforcer duration.

The present study investigated the effect of reinforcer duration on running and on responding reinforced by the opportunity to run. Eleven male Wistar rats responded on levers for the opportunity to run in a running wheel. Opportunities to run were programmed to occur on a tandem fixed-ratio 1 variable-interval 30-s reinforcement schedule. Reinforcer duration varied across conditions from 30 to 120 s. As reinforcer duration increased, the rates of running and lever pressing declined, and latency to lever press increased. The increase in latency to respond was consistent with findings that unconditioned inhibitory aftereffects of reinforcement increase with reinforcer magnitude. The decrease in local lever-pressing rates, however, was inconsistent with the view that response strength increases with the duration of the reinforcer. Response rate varied inversely, not directly, with reinforcer duration. Furthermore, within-session data challenge satiation, fatigue, and response deprivation as determinants of the observed changes in running and responding. In sum, the results point to the need for further research with nonappetitive forms of reinforcement.