Recommended housing conditions and test procedures can interact to obscure a significant experimental effect

Routine animal husbandry variables, such as group housing of mice and the order of testing of cagemates, are currently viewed to be essentially neutral with respect to the outcome of most, if not all, animal-based experiments, including those that utilize behavioral measurements. During the course of experiments that have utilized the elevated plus-maze to examine the ability of a bacterial challenge of mice to induce anxiety-like behavior, due to the activation of various cytokine pathways, we followed the recommendation of laboratory animal care staff to house the mice in pairs. When we tested the members of the pairs successively, it was found, for the first experimental set, that the behavior that reflects anxiety (time in closed arms) of the first-tested animal differed from that of the second-tested animal for both the experimental and the control animals and, critically, that these changes were in the opposite directions for the controls and the experimental animals, thus obscuring the effect of the experimental manipulation. A second, independent experimental set also obtained a significant effect for the order of testing effect in the bacterial-challenged group, but not in the saline control group, although a similar trend was evident in this group as well. These results indicate that special care should to be taken in implementing housing recommendations and that preliminary tests may be necessary to ensure that housing conditions do not interact with tests of the phenomenon under experimental investigation.     

Reliability of looking time

Twenty-eight college students viewed two sets of 30 color photographs each under instructions to look at each picture for as long as they wished. Equal thirds of the stimuli in each set were selected from high, middle, and low complexity levels. The sets were presented 7–10 weeks apart. The results indicated significant between- and within-session correlations that were not dependent on stimulus complexity. It was suggested that the findings were indicative of a consistency in either the rate at which Ss process information or the amount of information they process or both.     

The effect of UCS intensity in classical and avoidance GSR conditioning

This study compared GSR avoidance and yoked-control conditioning procedures. Classical conditioning at two UCS intensities was followed by extinction and, two months later, by an avoidance session. Matching of Ss was based on GSR responsiveness and classical conditioning in the first session. The strong UCS led to more rapid reduction in CR latency (due to an increase in number of Ss responding) in the first session, and there was a tendency for maximum CR magnitude to occur in fewer trials with the strong UCS. No UCS-intensity difference in level of responding to the CS or UCS was found in the first session. A greater amount of spontaneous recovery in the second session was found in the strong UCS group. The avoidance and yoked control groups did not differ in CR magnitudes, latencies, or frequencies, nor in UCR magnitudes in the second session. They did differ significantly in the rate of decline in intertriai responses, the decline being more rapid in the avoidance condition.     

Attention,extraversion, and stimulus—personality congruence

In this study Ss classified as extraverts, ambiverts or introverts on the Maudsley Personality Inventory looked at photographs rated as extravert, ambivert, or introvert for as long as they wished. It was hypothesized that there would be a tendency for Ss to look relatively longer at pictures congruent with their personality characteristic. Support for this hypothesis was found in a significant picture by personality interaction. Extraverts clearly looked longer at extravert pictures and introverts showed a very s light preference for introvert pictures. Ambivert pictures were looked at the longest by all groups. This high looking time for ambivert pictures and the small difference between the looking time at extravert and introvert pictures by introvert Ss is explained in terms of greater complexity of the ambivert and extravert pictures used in this experiment.     

Looking time: The effects of stimulus complexity and familiarity

During a 10 min. stimulus familiarization period, three groups of 60 Ss each received either 0, 10, or 20 sec. of familiarization on each of 30 experimental stimuli: 10 each of low, medium, and high stimulus complexity. All Ss then viewed the experimental stimuli in a second task, during which they could look at each stimulus for as long as they wished (free looking). For half the Ss in each group, free looking was administered immediately after the familiarization period. The remaining Ss received free looking 48 hr. later. The results replicated earlier research which has shown that free looking time is inversely related to stimulus familiarity, and directly related to stimulus complexity. Unlike earlier findings, the data suggested that with a 48 hr. delay between familiarization and free looking, a stimulus can, at least partially, recover from the decrement in looking time produced by 10 sec. of familiarization.     

The relationship between creativity and psychosis-proneness

One-hundred and fifteen undergraduates were repeatedly administered a battery measuring schizotypal personality type and creativity (remote associations). Principal Components Analysis found a two-factor model to be most parsimonious. The pattern of results suggests that magical ideation and perceptual aberration items are represented by one factor and suspiciousness by the second. Analysis of consistent versus inconsistent high scorers on the schizoptypia measure indicated that inconsistent high scorers on the suspiciousness factor scored significantly higher than consistent high scorers on the creativity measure.     

The role of dynamic information in the recognition of unfamiliar faces

The effects of movement on unfamiliar face recognition were investigated. In an incidental learning task, faces were studied either as computer-animated (moving) displays or as a series of static images, with identical numbers of frames shown for each. The movements were either nonrigid transformations (changes in expression) or rigid rotations in depth (nodding or shaking). At test, participants saw either single, static images or moving sequences. Only one experiment showed a significant effect of study type, in favor of static instances. There was no additional advantage from studying faces in motion in these experiments, in which both study types showed the same amounts of information. Recognition memory was relatively unaffected by changes in expression between study and test. Effects of viewpoint change were large when expressive transformations had been studied but much smaller when rigid rotations in depth had been studied. The series of experiments did reveal a slight advantage for testing memory with moving compared with static faces, consistent with recent findings using familiar faces. Future work will need to examine whether such effects may also be due to the additional information provided by an animated sequence.     

Neurobiology of Cocaine-Induced Organic Brain Impairment: Contributions from Functional Neuroimaging

The present review is directed at imparting the current knowledge regarding functional neuroimaging as a tool for enhancing the understanding of cerebrophysiologic and neurobehavioral consequences of stimulant abuse. Stimulants like cocaine are capable of inducing clinically significant neurocognitive impairment through direct action on the brain, and indirectly through other organs that influence cerebral physiology. Neurochemical dysregulation including profound effects on the serotonergic and dopaminergic systems have substantial physiological and neurobehavioral consequences. Brain hemorrhages, transient ischemic attacks, strokes, and seizures frequently follow cocaine use. The residual cerebropathologic consequences of cocaine are seen only in significant or pronounced brain events when structural neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) are employed. However, recent research with newer functional neuroimaging techniques such as single photon emission, positron emission tomography, and quantitative electroencephalography have revealed high rates of significant alteration in brain function among cocaine users, with negative structural imaging studies. These findings are often associated with impairment on neuropsychological evaluation, also in the absence of positive findings on CT and MRI. Both cerebral metabolic and hypoperfusion anomalies are seen, especially in anterior and temporal brain regions. Observed changes can persist for months, and for some patients, may represent a permanent change in brain functioning.     

Implicit learning of complex structures: active adaptation and selective processing in acquisition and application

Subjects exposed to members of a structured domain become sensitive to the general structure of that domain, even when they are unaware that the domain has such structure (e.g., Reber, 1993). Numerous investigators have attempted to characterize this learning as unselective in acquisition and automatic in application. However, we contend that this characterization miscasts the fundamental nature of learning. In a series of experiments, we demonstrate that what subjects learn implicitly about the structure of a domain critically depends on decisions they make about how to organize the structural components. Similarly, the application of knowledge gained implicitly is not stable, but may be selected or even created under the demands of the test task. We conclude that implicit learning, just like explicit learning, proceeds through active organization of the stimulus complex, rather than by passively absorbing any level of structure. We propose a synthesis, in which learning, with and without awareness, is understood through a common set of principles.     

Caretaker Psychological Factors Predicting Premature Termination of Children's Counseling

This study examines the psychological factors associated with caretakers' premature termination of counseling for their children. Data were collected on the 85 primary caretakers of 85 children in Texas who applied for counseling at community mental health centers or who received private practitioner care. The general hypothesis of the study was that scores on general hostility, intrapunitive hostility, extrapunitive hostility, paranoid ideation, depression, and anxiety would discriminate caretakers who prematurely terminated their children's counseling from both those caretakers whose children, in the judgment of the counselors, met therapeutic goals and those caretakers whose children did not meet therapeutic goals but who attended at least 10 counseling sessions. The effect size results suggest that counselors should primarily consider caretaker intrapunitive hostility when anticipating potential premature termination of counseling for children.