The effects of mental imagery on skin temperature and skin temperature sensation

In a series of six experimental sessions five subjects were instructed to imagine their hand in a hot and cold water stream. During the imagery period the subjects estimated with a psychophysical scale their subjective temperature sensations caused by the imagery. Skin temperature was measured from the thumb of the subjects' dominant hand. After each session the subjects were asked whether they had succeeded in producing an imagery. The skin temperature changes deviated significantly from the control level in the successful imagery experiments. Differences in the skin temperature changes between the successful and unsuccessful imagery experiments were significant. The skin temperature changes measured and the subjects' temperature sensations, produced by the imagery, were similar in the successful imagery experiments. The possible relationships between mental imagery and changes in skin temperature and skin temperature sensation are discussed.     

The effects of post-acquisition-trial sodium amylobarbitone on subsequent extinction behaviour

In a one-trial-per-day runway task, previously trained rats were injected via temporary intravenous cannulae with Sodium Amylobarbitone (SA) 15 mg/kg, or saline, immediately following each of six acquisition trials, according to one of four regimes. The animals were then extinguished with no further drug or saline treatments. Those that had been consistently reinforced (CR) and consistently treated with saline extinguished faster than those that had been partially reinforced (PR) and consistently treated with saline: the brief PR schedule thus generated a typical PR extinction effect. PR animals that had received SA treatments following nonrewarded trials and saline treatments following rewarded trials extinguished faster than those that had received the opposite treatments. Post-nonreward SA treatment during acquisition thus led to a pseudo CR extinction effect, while post-reward SA treatment in acquisition led to an undistorted PR extinction effect. The results are interpreted as showing that there is a critical period occurring between some tens of seconds and a very few minutes after frustrative nonreward which is vulnerable to SA in a non-state-dependent manner, and on which frustrative nonreward's control of subsequent behaviour depends.     

The effects of grouping visual stimuli on the cortical evoked potential

The University Of Michigan. Ann Arbor. Michigan The effect of grouping elements of a visual stimulus on the amplitude of the bipolar occipital evoked potential is considered in two experiments. A marked and orderly relation is found. Various classes of hypotheses are advanced to account for this finding.     

The potential effects of the implanted memory paradigm on child subjects

The purpose of this article is to examine the appropriate use of the implanted memory paradigm with children. In this paradigm, participants are asked repeatedly about fictitious events that never transpired. The responses of children in these investigations demonstrate clearly that they can be led to unintentionally create false memories. This article addresses whether memory research should continue to encourage children to create memories for events that never happened. The literature in other areas of psychology suggests that deception may lessen respect for authority, affect a child's self-esteem, and create stress. We propose that the use of the implanted memory paradigm be suspended indefinitely or until appropriate research demonstrates that the paradigm does not affect children negatively. © 1998 John Wiley & Sons, Ltd.     

The independent effects of skin tone and facial features on Whites' affective reactions to Blacks

Research on skin tone and Afrocentric features provides evidence that people use phenotypes (visible physical characteristics) to make inferences about the degree to which stereotypes about the racial group apply to the individual (i.e., to make impressions of others). However, skin tone and Afrocentric features have been confounded in prior research on this topic. The present study examines whether facial features (lip thickness, nose width) have effects on Whites' affective reactions to Black targets, above and beyond the well-documented skin tone effect by experimentally crossing variation in facial features and skin tone. The results showed that both skin tone and facial features independently affected how negatively, as opposed to positively, Whites felt toward Blacks using both implicit and explicit measures. The findings that Whites reacted more negatively toward Blacks with darker skin tone and more prototypical facial features than toward Blacks with lighter skin tone and less prototypical facial features on the explicit measure may indicate that Whites are unaware of the negative effects that Blacks' phenotypes can have on their racial attitudes. The present study demonstrated that subtle facial features, in addition to salient skin tone, also play an important role when predicting Whites' feelings about Blacks. One implication is that it is important to raise people's awareness about the effects that Blacks' phenotypes can have on their attitudes.     

The effects of implicit anxiety on the performance of skin self‐examinations

This study examined the effects of implicit anxiety on the performance of skin self‐examinations. It was hypothesized that implicit anxiety would contribute to the prediction of skin self‐examinations beyond the contributions of variables suggested by social‐cognitive models of health behavior. In addition, it was hypothesized that implicit anxiety's impact on self‐examinations would not be influenced by deliberative cognition about efficacy. To test these hypotheses, 128 participants completed measures of explicit anxiety, self and task efficacy, and an implicit associations test designed to measure implicit anxiety. As expected, self‐examination behavior was better predicted when implicit anxiety was added to models containing explicit anxiety and efficacy. Furthermore, thoughts about efficacy did not moderate the effects of implicit anxiety on self‐examination behavior.     

The potential effects of protected nests and cage complexity on maternal aggression in house mice

I studied the behavior of nursing house mice (Mus musculus) in captivity and used a two-by-two factorial design to test the hypothesis that the combination of a protected nest along with a chance for the intruders to retreat would improve the ability of resident females to defend their litters from infanticidal males. A chance for the intruder to retreat was manipulated by testing the resident females in either a single- or a two-compartment cage. The effect of a protected nest was examined by providing females with a nest box having a narrow entrance. During each test, an infanticidal adult male was introduced into the cage of a resident female and her pups. I observed that neither the presence of a protected nest nor the chance for the intruders to retreat to a different compartment, or a combination of the two, increased the ability of a female to defend her litter against an intruder male. Moreover, neither of these two factors influenced the overall behavior of the resident females. I obtained similar results after using data from previous studies to examine the influence of both of these factors on the efficiency of maternal aggression. Overall, these two approaches showed that females are often unable to prevent intruders from committing infanticide. I discuss the validity of the hypothesis that maternal aggression evolved as a mechanism to protect offspring from infanticide. Aggr. Behav. 24:385–396, 1998. © 1998 Wiley-Liss, Inc.     

The number of active palmar sweat glands (palmar sweat index,PSI) as an activation measure in field studies

The number of active sweat glands within a defined area of a fingertip, called the palmar sweat index (PSI), can be easily determined by means of the plastic fingerprint method. Two experiments were carried out to demonstrate the applicability of this technique in field research and to investigate the properties of the PSI as an activation parameter. In Experiment 1 (in a blood donors’ ward), PSI rose significantly during venous puncture and dropped after the cannula had been installed. In Experiment 2 (in a dental office), PSI values increased when patients were seated in the dental chair and rose to a higher level at the dentist’s entry. Values after treatment were significantly lower. In both experiments, it was observed that the initial assessments yielded higher PSI values. This is best explained as a reaction to the assessment procedure itself, and it is recommended that the first two prints not be used for the determination of baseline values.     

Operant behavior and the galvanic skin potential under DRL schedule

Motor and galvanic skin potential (GSP) activity were investigated during the conditioning, extinction, and reconditioning of motor responses under a differential reinforcement of low rate (DRL) schedule of reinforcement. Interresponse time (IRT) distributions for motor responses during conditioning and reconditioning gradually stabilized at a peak just beyond the minimal IRT required for reinforcement. Few unreinforced motor responses and "bursts" of motor responses were observed during conditioning and reconditioning. Relative to conditioning and reconditioning, extinction effected larger IRTs and smaller GSP amplitudes. GSP amplitudes were greater for unreinforced than for reinforced motor responses during conditioning and reconditioning. However, GSP amplitudes associated with the unreinforced extinction responses were smaller than either the reinforced or unreinforced responses during conditioning and reconditioning.     

Event-related potential correlates of interference effects on recognition memory

The question of interference (how new learning affects previously acquired knowledge and vice versa) is a central theoretical issue in episodic memory research, but very few human neuroimaging studies have addressed this question. Here, we used event-related potentials (ERPs) to test the predictions of the complementary learning systems (CLS) model regarding how list strength manipulations (strengthening some, but not all, items on a study list) affect recognition memory. Our analysis focused on the FN400 old-new effect, a hypothesized ERP correlate of familiarity-based recognition, and the parietal old-new effect, a hypothesized ERP correlate of recollection-based recognition. As is predicted by the CLS model, increasing list strength selectively reduced the ERP correlate of recollection-based discrimination, leaving the ERP correlate of familiarity-based discrimination intact. In a second experiment, we obtained converging evidence for the CLS model’s predictions, using a remember/know test: Increasing list strength reduced recollection-based discrimination but did not reduce familiarity-based discrimination.     

The potential for experimenter bias effects in word recognition experiments

Word recognition experiments that involve comparisons between two different matched sets of words allow for possible experimenter bias if there are many equally well-matched pairs to choose from. The possible extent of this bias depends on the experimenter's intuitive knowledge of the likely difficulty of individual items. This is assessed by asking a number of experimenters to decide which of two frequency-matched words would produce the fastest reaction time in a lexical decision experiment, and then comparing their predictions with actual data. All experimenters demonstrated substantial above-chance accuracy, which was unrelated to the amount of experience they had in the field. It was concluded that the experimenters could potentially produce spurious effect sizes ranging from 16 to 38 msec.