Psychophysiology

The purpose of this study was to determine the extent to which preadaptation to differential brightness magnitude affects responses to a constant postadaptation stimulus. Twenty-four male albino rats, one hundred and tweny days old, were divided into four groups and differentially preadapted in Skinner-boxes to 236.90, 77.25, 22.87, and 1.27 apparent foot-candles for 10 minutes, without access to a bar. Immediately following this period the Ss were allowed to respond under continuous reinforcement to a postadaptation stimulus of 236.90 apparent foot-candles. Measurement in terms of bar pressing indicated that the four groups extinguished differentially over six days. The control group, for whom the discrepancy bwtween preadaptation magnitude and postadaptation stimulus remained zero, was found most resistant to extiction during this period. Additionally, increases in the discrepancy between the pre- and postadaptation magnitudes led to experimental groups. The implications of these data for the proposition of stimulus definitions in terms of behaviorally effective magnitudes were discussed.

Agency and communion are fundamental dimensions underlying psychological
processes. Although agency and communion are coherent dimensions, their origins,
nature, stability differ across theoretical framework. Common to these frameworks are
gender differences in agency and communion. The present study hypothesized that
because agency and communion relate to gender, they may also relate to digit ratio. The
present study is important because digit ratio may offer clues on the origins and nature of
agency and communion, and their gender differences. Agency and Communion factors
were extracted from implicit linguistic measures obtained by LIWC analysis of selfnarratives.
Exploratory structural equation modeling indicated communion related to digit
ratio in men, and gender differences in communion. Although the results supported the
distal, biological influences of communion argued by evolutionary accounts, the null
finding agency was not related to digit ratio, while not directly interpretable, did not
contradict socialization accounts of agency.

Many studies have supported the overall health benefits of mindfulness meditation practices for adults, but research exploring such benefits for children is sparse. The present study explored the psychophysiological effects of mindfulness meditation over a 10 week-period on a sample of 2nd-and 4th-grade children. Electroencephalograph (EEG) asymmetry and coherence were recorded at baseline and immediately after the meditation intervention for the experimental group, and at baseline and after 10 weeks for the control group. Measures of affect, behavioral motivation, creativity, and depression were also administered. The primary findings indicated that when improvement in depressive symptoms occurred for 4th-grade students who were somewhat engaged in meditation practice, left-sided frontal EEG activity was also more prominent. Additionally, 4th-grade students who actively participated in meditation practice experienced decreases in self-reported levels of negative affect. Results suggest that mindfulness meditation is beneficial for improving 4th-grade students’ mood and brain regions associated with mood.

The adequacy of the learned helplessness and motor activation deficit interpretations of the interference effect
were tested. Artificially increasing motor activity by
administration of several levels of d-amphetamine failed
to attenuate the interference effect. No differential
effects of drug treatment between naive animals and animals
pretreated with inescapable shock were found in an activity
task. Both interpretations of the interference effect
would adequately explain the results.

According to the cardiac-somatic hypothesis, heart rate
changes are a function of changes in somatic activity. Conversely,
the Independent Response Theory states that conditioning
of heart rate and somatic activities are independent
of each other. Using two groups, the present study examined
these conflicting theories by measuring changes in heart
rate and bar press suppression during 10 days of CER and
passive avoidance conditioning. Results of this study
indicate that heart rate responses and bar press suppression
conditioned independently of each other, during both CS and
post CS periods. Further, while bar pressing suppressed
rapidly in both groups, heart rate responses were different
between the two groups suggesting that although both
procedures conditioned the same behavioral results, they
elicit different autonomic responses.

The literature regarding biological motion suggests that people may accurately identify and recognize the gender of others using movement cues in the absence of typical identifiers. This study compared identification and gender judgments of traditional point-light stimuli to skeleton stimuli. Controlling for previous experience and execution of actions, the frequency and familiarity of movements was also considered. Watching action clips, participants learned to identify 4 male and 4 female actors. Participants then identified the corresponding point-light or skeleton displays. Although results indicate higher than chance performance, no difference was observed between stimuli conditions. Analyses did show better gender recognition for common as well as previously viewed actions. This suggests that visual experience influences extraction and application of biological motion. Thus insufficient practice in relying on movement cues for identification could explain the significant yet poor performance in biological motion point-light research.

Resource allocation theory, Polich (2007) suggests cortical measures may attenuate when processing demands increase. Thirteen HIV-negative women (M = 36.5) and 15 HIV-positive women (M = 36.1) infected were instructed to view neutral and negative IAPS images and then to detect rare tones in a subsequent auditory oddball task. A 2 x 2 ANOVA for the auditory P3 did not indicate a main effect for picture valence however an interaction was found between picture valence and serostatus at location Fz, F(1,24) = 18.99, p<.001. During the visual ERP sequence an interaction between valence and serostatus was found at the Pz location, F(1,24) = 18.99, p<.001, meaning the late positive potential (LPP) was not modulated between viewing neutral and negative images in HIV-positive women. These findings suggest that the manifestation of HIV in women may alter the neural processing of emotions, though not to the detriment of a subsequent cognitive task.

The human prefrontal cortex (PFC) is associated with complex cognitive behaviors such as planning for the future, memory for serial order, social information processing and language. Understanding how the PFC has changed through time is central to the study of human neural evolution. Here we investigate the expansion of the PFC by measuring relative surface area of the PFC in Pan troglodytes and Homo sapiens. Magnetic resonance images (MRI's) from 8 preserved chimpanzee brains (3 male and 5 female adults) were segmented and measured. The results of this study indicate that there are gross anatomical differences between the chimpanzee and human prefrontal cortex beyond absolute size. The lower surface area to volume ratio in PFC of the chimpanzee when compared to a human indicates less gyral white matter in this region and thus, less associative connectivity. This anatomical evidence of a difference corresponds with the lesser cognitive complexity observed in chimpanzees.