Threshold estimation in two-alternative forced-choice (2AFC) tasks: the Spearman-Kärber method

The Spearman-K?rber method can be used to estimate the threshold value or difference limen in two-alternative forced-choice tasks. This method yields a simple estimator for the difference limen and its standard error, so that both can be calculated with a pocket calculator. In contrast to previous estimators, the present approach does not require any assumptions about the shape of the true underlying psychometric function. The performance of this new nonparametric estimator is compared with the standard technique of probit analysis. The Spearman-K?rber method appears to be a valuable addition to the toolbox of psychophysical methods, because it is most accurate for estimating the mean (i.e., absolute and difference thresholds) and dispersion of the psychometric function, although it is not optimal for estimating percentile-based parameters of this function.     

Effects of redundant visual stimuli on temporal order judgments

Four experiments were conducted in order to compare the effects of stimulus redundancy on temporal order judgments (TOJs) and reaction times (RTs). In Experiments 1 and 2, participants were presented in each trial with a tone and either a single visual stimulus or two redundant visual stimuli. They were asked to judge whether the tone or the visual display was presented first. Judgments of the relative onset times of the visual and the auditory stimuli were virtually unaffected by the presentation of redundant, rather than single, visual stimuli. Experiments 3 and 4 used simple RT tasks with the same stimuli, and responses were much faster to redundant than to single visual stimuli. It appears that the traditional speedup of RT associated with redundant visual stimuli arises after the stimulus detection processes to which TOJs are sensitive.     

A neuropsychiatric developmental model of serial homicidal behavior

Serial sexual homicide has been the object of intensive study from forensic psychiatric, criminological, developmental, and sociological perspectives. In contradistinction to these approaches, neuropsychiatric concepts and methods have received relatively little attention in this area. In this article we adopt a neuropsychiatric developmental perspective and undertake a review of the psychiatric literature on violence and autism spectrum disorders. Our analysis of this literature suggests the presence of an association between autism spectrum psychopathology and serial homicidal behavior. Recommendations for further research to help clarify the nature of this association are briefly discussed.     

The ontogeny of serial-order behavior in humans (Homo sapiens): representation of a list

The authors trained 3-, 4-, 7-, and 10-year-old children and adults (Homo sapiens) on a nonverbal serial-order task to respond to 5 items in a specific order. Knowledge of each item's sequential position was then examined using pairwise and triplet tests. Adults and 7- and 10-year-olds performed at high levels on both tests, whereas 3- and 4-year-olds did not. The latency to respond to the first item of a test pair or triplet was linearly related to that item's position in the training series for the 7- and 10-year-olds and adults, but not for the 3- and 4-year-olds. These data suggest that older children and adults, but not younger children, developed a well-integrated internal representation of the serial list.     

Emotional-processing in posttraumatic stress disorder II: startle reflex modulation during picture processing

This study examined the impact of a trauma-related stressor on subsequent emotional behavior in veterans with (n = 35) and without (n = 24) posttraumatic stress disorder (PTSD). Self-report and physiological responses, including acoustic startle, were recorded during viewing of emotionally evocative photographs at baseline and following exposure to trauma-related and non-trauma-related stressors. The 2 groups exhibited equivalent patterns of emotional response across self-report and physiological measures at baseline. In contrast, following the trauma challenge, participants with PTSD showed a pattern of startle modulation suggestive of greater defensive reactivity and reduced visual perceptual engagement. These findings, along with augmented corrugator EMG reactivity during the same interval, suggest that trauma-related reexperiencing primes subsequent negative emotional responding in individuals with PTSD.     

Cognitive vulnerability to depression: a taxometric analysis

Although there is increasing support for the hypothesis that negative cognitive styles contribute vulnerability to depression, it remains unclear how best to conceptualize the heterogeneity in cognitive vulnerability to depression. Specifically, does this heterogeneity reflect quantitative or qualitative differences among individuals? The goal of this study was to address this question by examining whether the underlying structure of cognitive vulnerability to depression is best conceptualized as dimensional or categorical. Taxometric analyses provided consistent support for the dimensional nature of negative cognitive styles. It appears, therefore, that cognitive vulnerability to depression is best conceptualized as a dimensional construct, present to a greater or lesser extent in all individuals. Despite this, the strength of the relationship between negative cognitive styles and depressive symptoms does appear to vary as a function of where along the cognitive style continuum one falls.     

Social anxiety in stuttering: measuring negative social expectancies

Much research has suggested that those who stutter are likely to be anxious. However, to date, little research on this topic has addressed the role of expectancies of harm in anxiety, which is a central construct of anxiety in modern clinical psychology. There are good reasons to believe that the anxiety of those who stutter is related to expectancies of social harm. Therefore, in the present study, 34 stuttering and 34 control participants completed the Fear of Negative Evaluation (FNE) Scale and the Endler Multidimensional Anxiety Scales-Trait (EMAS-T). The FNE data showed a significant difference between the stuttering and control participants, with a large effect size. Results suggested that, as a group, a clinical population of people who stutter has anxiety that is restricted to the social domain. For the EMAS-T, significant differences between groups were obtained for the two subtests that refer specifically to people and social interactions in which social evaluation might occur (Social Evaluation and New/Strange Situations) but not for the subtests that contained no specific reference to people and social interactions (Physical Danger and Daily Routines). These results were taken to suggest that those who stutter differ from control subjects in their expectation of negative social evaluation, and that the effect sizes are clinically significant. The findings also suggest that the FNE and the EMAS-T are appropriate psychological tests of anxiety to use with stuttering clients in clinical settings. The clinical and research implications of these findings are discussed, in terms of whether social anxiety mediates stuttering or is a simple by-product of stuttering. Possible laboratory explorations of this issue are suggested, and potential Cognitive Behavior Therapy packages for stuttering clients who might need them are discussed. EDUCATIONAL OBJECTIVES: The reader will be able to: (1) explain why expectancy of social threat or harm may be associated with stuttering; (2) name and describe two psychological tests that are suitable for assessment of the social threat or harm that may be associated with stuttering; and (3) explain how findings for the EMAS-T test in the present results suggest that expectancy of social threat or harm, but not other kinds of negative expectancy, are associated with stuttering.     

The US-preexposure effect in lithium-induced flavor-aversion conditioning is a consequence of blocking by injection cues

In 2 experiments, rats received flavor-aversion conditioning in which the unconditioned stimulus (US) was an orally consumed solution of lithium chloride (LiCl). The resulting aversion was not attenuated by giving preexposure to injections of LiCl, although such preexposure did attenuate aversions established using injected LiCl as the US (Experiment 1). This outcome suggests that blocking by injection-related cues is responsible for the US-preexposure effect observed in this situation. Experiment 2 confirmed this interpretation by showing that presenting such cues (by giving an injection of saline) at the time that the LiCl was drunk resulted in an attenuation of conditioning in animals preexposed to injections of LiCl. The US-preexposure effect obtained in these experiments can be explained solely in terms of blocking by injection cues, although other mechanisms may contribute to the effect seen in other flavor-aversion paradigms.     

Temporal coding in conditioned inhibition: analysis of associative structure of inhibition

Two experiments with rats as subjects were conducted to investigate the associative structure of temporal control of conditioned inhibition through posttraining manipulation of the training excitor-unconditioned stimulus (US) temporal relationship. Experiment 1 found that following simultaneous Pavlovian inhibition training (i.e., A --> US/XA-no US) in which a conditioned stimulus (CS A) was established as a delay excitor, maximal inhibition was observed on a summation test when CS X was compounded with a delay transfer CS. Furthermore, posttraining shifts in the A-US temporal relationship from delay to trace resulted in maximal inhibition of a trace transfer CS. Experiment 2 found complementary results to Experiment 1 with an A-US posttraining shift from serial to simultaneous. These results suggest that temporal control of inhibition is mediated by the training excitor-US temporal relationship.     

Body image variability: the influence of body-composition information and neuroticism on young women's body dissatisfaction

The current studies consider the effect of body size, body composition feedback, and the moderating influence of neuroticism (N) on three measures of body dissatisfaction (BD) in young women. In Study One, normal-sized subjects who were given false feedback indicating that they were either fatter or leaner than average showed heightened BD compared to groups who received either accurate or no feedback about body size. There was no evidence of a moderating effect of N. In Study Two, thinner-than-average subjects who received accurate body-size feedback showed greater satisfaction than a control group receiving no information. For heavier than average subjects, feedback only increased BD for those low on N. Although these results show mixed support for N as a moderator, they are the first to show an effect of body composition information on BD.