Use of a computer-controlled firearms training simulator in perception response time experiments

This paper describes the use of a custom-configured computer-controlled firearms training simulator to measure perception response (reaction) time (RT) to a stimulus in which the degree of threat presented is a manipulable variable across trials. The computer records the number of frames of videotape traversed between the point of presentation of the threat in the video stimulus and the point at which the subject responds by drawing the firearm. For the purposes of data analysis, these frame-count measures are converted to RT measurements. Example data are presented that capture perception RT at both thedraw-stimulus and thefire-stimulus points in situations for which either only one threat or more than one threat exists. Other elements, such as degree of threat and accuracy of response, provide additional data.     

An auto-adjusting shaping procedure

A variable interval (VI) schedule is described that automatically adjusts the programmed rates of reinforcement in accordance with the rates of responding of subjects during the two immediately preceding 30-sec time intervals. The schedule prescribes that as rate of responding decreases, programmed reinforcement rate increases, and that when rate of responding increases, reinforcement rate decreases. Thus, programmed reinforcement rate is adjusted continuously until some target value is reached. Ten rats were exposed to this procedure five times a day at 1-h intervals. The target, set at VI 120 sec, was reached by most subjects within 4 days of training. Subsequently, all subjects responded consistently during five daily 1-h sessions with VI 120 sec. This procedure speeds up the training of subjects on long VI schedules and substantially reduces the time and effort spent observing the subjects and adjusting the schedule parameter value during the early development of responding.     

Determination of the variation in conduction speed of motor fibers and the effects of diphenylhydantoin (Phenytoin) and diazepam (Faustan)]

The variation in the speed of conduction of motor fibers of the ulnar nerve was determined by Hopf's double-stimulus method and compared with values obtained from the duration of muscular response potentials for differently spaced points of stimulation. However, the values obtained from the difference of the duration of response potentials are inadequate since the duration of potentials cannot always be determined accurately. After a ten-day administration of faustan (15 mg per day) or phenytoin (300 mg per day) there was observed a decrease especially in the minimum rate of conduction of motor fibers of the ulnar nerve.     

Sensitivity to social contingencies between 1 and 3 months of age

Infants' sensitivity to social contingencies was assessed. In Study 1, 1-month-old infants and their mothers interacted face-to-face in three types of imperfect contingent interactions: Normal, Non-Contingent and Imitation. One-month-old infants did not discriminate these conditions. In Study 2, 3-month-old infants were tested as in Study 1. At 3 months of age, infants gazed reliably longer in the Imitation condition and smiled reliably more in the Normal than in the Non-Contingent and Imitation interactions. These findings suggest a developmental transition in the sensitivity to social contingencies between 1 and 3 months of age. The relationship between the developing sensitivity to social contingencies and social cognition is discussed.     

Sensitivity to triadic attention in early infancy

In Study 1, 54 3-, 6- and 9-month-old infants interacted with an adult stranger who engaged in a face-to-face (dyadic) exchange. Dyadic interaction was halted when the adult turned away to look at an object. In a Joint Attention condition, the adult alternated visual attention between the infant and the object, and in a Look Away condition she looked away at the object only. Infants gazed and smiled more in the Joint Attention condition compared to in the Look Away condition. Infants' gazing to the target object interacted with age and condition. In Study 2, 37 3-, 6- and 9-month old infants interacted with an adult who coordinated visual attention and affect, affect only, visual attention only, or ignored the infant. Infants gazed reliably more at E when she coordinated both affect and attention and smiled reliably more when the adult coordinated affect and attention or attention only. The findings show a sensitivity to triadic attention by 3 months of age.     

Selective impairment of auditory selective attention under concurrent cognitive load

Load theory predicts that concurrent cognitive load impairs selective attention. For visual stimuli, it has been shown that this impairment can be selective: Distraction was specifically increased when the stimulus material used in the cognitive load task matches that of the selective attention task. Here, we report four experiments that demonstrate such selective load effects for auditory selective attention. The effect of two different cognitive load tasks on two different auditory Stroop tasks was examined, and selective load effects were observed: Interference in a nonverbal-auditory Stroop task was increased under concurrent nonverbal-auditory cognitive load (compared with a no-load condition), but not under concurrent verbal-auditory cognitive load. By contrast, interference in a verbal-auditory Stroop task was increased under concurrent verbal-auditory cognitive load but not under nonverbal-auditory cognitive load. This double-dissociation pattern suggests the existence of different and separable verbal and nonverbal processing resources in the auditory domain.     

Dissociable stages of problem solving (I): temporal characteristics revealed by eye-movement analyses

Understanding the functional neuroanatomy of planning and problem solving may substantially benefit from better insight into the chronology of the cognitive processes involved. Based on the assumption that regularities in cognitive processing are reflected in overtly observable eye-movement patterns, here we recorded eye movements while participants worked on Tower of London (TOL) problems that comprised an experimental manipulation of different task demands. Single-trial saccade-locked analyses revealed that higher demands on forming an internal problem representation were associated with an increased number of gaze alternations between start state and goal state, but did not show any effect on the durations of these inspections of the states. In contrast, higher demands on actual planning in terms of mental manipulations of working memory contents coincided with a prolonged duration of the very last inspection of the start state (i.e., immediately preceding movement execution) but did not show any effect on the number of gaze alterations. Differential task demands on internalization and planning processes during problem solving hence selectively affect different eye-movement parameters. Moreover, these findings complement previous neuroimaging data on dissociable contributions of left and right dorsolateral prefrontal cortex in problem solving with novel evidence for a corresponding dissociation in the eye-movement patterns reflecting the associated cognitive processes.     

Dimensions and Latent Classes of Episodic Mania-Like Symptoms in Youth: An Empirical Enquiry

The dramatic increase in diagnostic rates of bipolar disorder in children and adolescents in the USA has led to an intense interest in the phenomenology of the disorder. Here we present data from a newly-developed instrument to assess episodic mania-like symptoms in youth in a large population-based sample (N = 5326) using parent- and self-report. We found that a substantial proportion of children screened positive for having episodes of “going high” and were at an increased risk for morbidity and impairment. Using factor analysis, we identified that episodic mania-like symptoms comprised two dimensions: An under-controlled dimension that was associated with significant impairment, and a low-risk exuberant dimension. Using latent class analysis, we identified a small group of children scoring high on a range of manic symptoms and suffering from severe psychosocial impairment and morbidity. Our results carry implications for the nosology and psychosocial impairment associated with episodic mood changes in young people.     

Should DBS for Psychiatric Disorders be Considered a Form of Psychosurgery? Ethical and Legal Considerations

Deep brain stimulation (DBS), a surgical procedure involving the implantation of electrodes in the brain, has rekindled the medical community’s interest in psychosurgery. Whereas many researchers argue DBS is substantially different from psychosurgery, we argue psychiatric DBS—though a much more precise and refined treatment than its predecessors—is nevertheless a form of psychosurgery, which raises both old and new ethical and legal concerns that have not been given proper attention. Learning from the ethical and regulatory failures of older forms of psychosurgery can help shed light on how to address the regulatory gaps that exist currently in DBS research. To show why it is important to address the current regulatory gaps within psychiatric DBS, we draw on the motivations underlying the regulation of earlier forms of psychosurgery in the US. We begin by providing a brief history of psychosurgery and electrical brain stimulation in the US. Against this backdrop, we introduce psychiatric DBS, exploring current research and ongoing clinical trials. We then draw out the ethical and regulatory similarities between earlier forms of psychosurgery and psychiatric DBS. As we will show, the factors that motivated strict regulation of earlier psychosurgical procedures mirror concerns with psychiatric DBS today. We offer three recommendations for psychiatric DBS regulation, which echo earlier motivations for regulating psychosurgery, along with new considerations that reflect the novel technologies used in DBS.     

Multiple sources of positive- and negative-priming effects: An event-related potential study

Event-related potential correlates of positive priming (PP) and negative priming (NP) were investigated in order to further elucidate the cognitive mechanisms involved. Thirty-six participants performed both an identity- and a location-based priming task. Repeating the target stimulus/location from the immediately preceding display produced behavioral PP. With localization, but not with identification, behavioral NP was observed when the target stimulus/location matched the preceding distractor stimulus/location. Smaller P300 amplitude accompanied identity-based PP, suggesting persisting target-specific activation. The lateralized readiness potential, an index of correct/incorrect response activation, indicated persisting central motor activation as another source of PP. Both location-based PP and NP were accompanied by reduced P1/N1 and P300 amplitudes, pointing to the involvement of inhibition of return in location-based priming. The results support the view that multiple brain processes underlie behavioral priming.