High Impulsive Subjects Research Articles

Reward sensitivity in impulsivity.

Impulsive individuals choose immediate small over delayed larger rewards, suggesting reward hypersensitivity. Single-unit studies have shown increased ventral tegmental activity to rewards and reward predictors and decreased activity when predicted rewards are withheld. The orbitofrontal ventral tegmental cortical target also responds to reward and expectation in single-unit and neuroimaging studies. The anterior P2a event-related potential component is a proposed index of reward-related orbitofrontal activity. In this reward prediction study in high and low impulsive subjects, the P2a localized to orbitofrontal cortex and was largest to non-predicted rewards and smallest in the absence of predicted rewards in subjects higher on self-reported impulsiveness, consistent with a P2a index of orbitofrontal reward processing and with reward hypersensitivity in impulsivity.

Personality, event-related potential (ERP) and heart rate (HR) in emotional word processing

Gray's theory asserts that anxiety is associated with high sensitivity to signals of punishment and impulsivity with high sensitivity to signals of reward. These hypotheses were tested by engaging subjects in four emotional-word recognition tasks using a visual oddball paradigm . Each task was formed by combining standard and target stimuli with respect to emotional valence of the words (positive-standard/positive-target, positive-standard/negative-target, negative-standard/positive-target, negative-standard/negative-target). For target words the following measures were obtained: (1) peak amplitude and latency of the P3 ERP component; (2) heart rate change; (3) reaction time; (4) emotional feeling ratings. Orthogonal personality dimensions of impulsivity and anxiety were derived from a mutual analysis of popular personality and temperamental scales. The results showed higher P3 peaks over parietal and occipital leads when target words had an opposite emotional valence to standard ones. More pronounced HR decelerations were also obtained for these conditions. Across frontal and temporal recording sites, P3 amplitude was larger in high-anxiety subjects than in low-anxiety ones for unpleasant words, suggesting higher sensitivity to negative emotions. High-anxiety subjects also displayed higher emotional ratings and more pronounced HR decelerations to unpleasant targets. High impulsivity subjects, compared to low impulsivity ones, showed smaller P3 peaks for negative valenced targets mainly over parietal and occipital cortical regions and longer P3 latencies across all recording sites. The expected amplification of the response to negative emotion in the high anxiety group was confirmed, but the corresponding prediction for impulsiveness and positive emotion was not supported. These findings, however, appear in line with the “joint subsystems” hypothesis (Corr, 2002) that predicts a lower level of sensitivity to signals of punishment in high impulsivity subjects.

Impulsiveness and arousal: heart rate under conditions of rest and challenge in healthy males

Abstract Personality theory has proposed that the impulsive individual may be characterized physiologically by resting under-arousal along with greater increases in arousal when stimulated. Previously physiological measurement of impulsivity has primarily been conducted using electrocortical techniques in pathological samples. However, the current study tests the theory relating impulsivity and arousal using heart rate measures in healthy men scoring either high ( n =14) or normal ( n =14) on the Barratt Impulsiveness Scale. Heart rate was measured under two conditions; (1) rest, and (2) challenge (Paced Auditory Serial Attention Task, a cognitively demanding procedure of moderate duration and increasing intensity). High impulsive subjects exhibited generally slower heart rate under conditions of rest along with greater relative reactivity under a challenge condition (although this effect was reversible under continued increasing stimulation). These results are consistent with under-arousal theory of impulsivity and support the continued use of heart rate measures for addressing impulsivity theory.

Are high-impulsive and high risk-taking people more motor disinhibited in the presence of incentive?

In this study we assess the ability to inhibit certain planned actions in relation to the impulsiveness and venturesomeness traits of personality using the stop-signal paradigm. In the first condition subjects performed the stop-signal task without incentives. In the second condition, subjects performed the same task using an approach-avoidance conflict situation: speed of response was rewarded and the lack of inhibition was punished. Twenty male subjects were selected after preliminary testing using the impulsivity subscale from the Eysenck Personality Inventory. The main findings were: (1) no deficit in motor inhibition was found for high-impulsive subjects; estimated mean reaction times of inhibitory processes were the same for both high- and low-impulsive groups and (2) the presence of an incentive in the conflict situation affected motor inhibition for low venturesomeness subjects, who adopted a more cautiousness response strategy.

Caffeine differentially affects kinesthetic aftereffect in high and low impulsives

The effects of caffeine on kinesthetic aftereffect (KAE) were examined. Following a between-subjects design, high and low impulsive male postgraduate students were administered placebo and four doses of caffeine (1, 2, 3 and 4 mg/kg body weight) in a laboratory situation. A double blind procedure was adopted for drug administration. The study supports the following conclusions: (1) caffeine reduces KAE in high impulsive subjects; (2) the larger dose of caffeine (4 mg/kg) enhances KAE in low impulsive subjects; (3) caffeine produces profound effects on the performance of high impulsives; (4) caffeine leads to different dose-response trends in the two groups.

Differential effects of reward and punishment cues on response speed in anxious and impulsive individuals

Four groups of subjects—neurotic extraverts, stable extraverts, neurotic introverts, and stable introverts—were instructed to trace a circle template as slowly as possible. The tracing task was performed under one of three conditions: Condition Rw entailed the presence of reward cues, Condition Pn entailed the presence of punishment cues, and Condition G(while involving the presence of goal stimulus) entailed neither type of conditioned stimulus. As predicted, high impulsive (neurotic extravert) subjects exhibited inappropriately rapid tracing speeds (i.e. behaved impulsively) to a greater extent than did low impulsive (stable introvert) subjects in Conditions Rw. Although, as expected, high anxious (neurotic introvert) subjects manifested the fastest tracing speeds among the four subject groups in the presence of punishment cues (i.e. in Condition Pn), they did not trace significantly faster than low anxious (stable extravert) subjects. Finally, replicating earlier research in which the presence of a salient goal stimulus was sufficient to engender rapid responding, high impulsive subjects traced significantly faster than did low impulsives in Condition G. These results are discussed in the context of a model of impulsive behavior that is primarily a synthesis of Eysenck's ( The biological basis of personality, 1967) personality theory and Gray's ( Elements of a two-process theory of learning, 1975) three arousal model. This synthesis maps the extraversion dimension onto the relative strengths of Gray's behavioral activation and inhibition systems, and identifies the neuroticism dimension with Gray's nonspecific arousal system.

Impulsiveness and anxiety: Information processing and electroencephalograph topography

Within a general systems model of personality, we are currently studying impulsiveness and other personality traits using multitrait-multimethod multivariate designs. The research involves a wide spectrum of techniques in an effort to find consistent relationships among biological, cognitive, behavioral, and environmental correlates of the personality traits. The goal is to develop unique profiles of personality traits based on these four classes of measurements. Our research has demonstrated that impulsiveness and anxiety are personality traits that have loadings on two orthogonal higher order personality factors that we have labeled action-oriented and mood-feeling. From both an empirical research and a clinical viewpoint, we have identified three subtraits of impulsiveness: cognitive (Ic), motor (Im), and nonplanning (Inp). Inp is hypothesized to relate to frontal lobe brain processes, while Ic and Im are more related to neural mechanisms that (1) control performance on tasks with “timing-and-rhythm” demands and/or (2) are related to seizure disorders. High-impulsive subjects (especially when high on Ic and Im) are less efficient at performing a wide range of psychomotor tasks. We hypothesize that this inefficiency relates to the information-gating properties of the nervous system being out of “synch” with efficient performance of selected tasks. High-impulsive subjects are visual N100 event-related potential augmentors, which would be consistent with this dyssynchrony occurring in the early stages of information processing. We also hypothesize that impulsiveness is related to serotonin (high impulsiveness related to low serotonin levels). Our psychopharmacological-psychophysiological studies of information processing would be consistent with the latter hypothesis.

The biological basis of impulsiveness: the significance of timing and rhythm disorders

High-impulsive subjects often do say things on the spur of the moment and/or make up their minds quickly. The description of impulsivity as a personality trait involves a number of basic research questions including: 1. 1. From a psychometric viewpoint, how inclusive or broad is impulsivity as a personality trait? 2. 2. How does impulsivity relate to other personality traits? 3. 3. Is there a pattern of biological correlates of impulsivity that is distinct from other personality traits? 4. 4. What is the relationship between cognitive and behavioral impulsivity? This paper addresses those four questions. Psychometric analysis of issues in impulsivity indicates the need for a distinction between broad and narrow impulsivity traits and further redefinition of the latter in terms of cognitive and motor components. This research has also shown that impulsiveness has an orthogonal relationship with measures of anxiety. In perceptual-motor tasks, high-impulsive subjects perform less efficiently and with greater variability on a wide range of these tasks, and in particular when the task involves responding to two or more sequential stimuli. High-impulsive subjects underproduce time intervals in time-judgment tasks; this and other findings suggest that high-impulsive subjects have a faster cognitive tempo than low-impulsive subjects. The interaction of impulsivity and anxiety in the performance of perceptual-motor tasks is also reflected in psychophysiological measures; differences in impulsivity are more evident with electrocortical measures and differences in anxiety are reflected in ANS measures while performing the tasks.