General Impulse Research Articles

Stopping at the sight of food – How gender and obesity impact on response inhibition

Recent research indicates that reduced inhibitory control is associated with higher body mass index (BMI), higher food craving and increased food intake. However, experimental evidence for the relationship between response inhibition and weight status is inconsistent and to date has been investigated predominantly in women. In the current study, 56 participants (26 obese, 30 lean; 27 female, 29 male) performed a Food Picture Rating Task followed by a Stop Signal Task where pictures of palatable high or low caloric food or non-food items were presented prior to the Go signal. We further assessed participants’ self-reported eating behavior and trait impulsivity as potential factors influencing response inhibition, in particular within the food context. Independent of BMI, women showed significantly higher liking for low caloric food items than men. This was accompanied by shorter Stop Signal Reaction Times (SSRT) after high compared to low caloric food pictures for women, and shorter SSRT in women compared to men for high caloric food. No influence of gender on SSRT was observable outside of the food context. While SSRTs did not differ between obese and lean participants across the three picture categories, we found a moderating effect of trait impulsivity on the relationship between BMI and SSRT, specifically in the high caloric food context. Higher BMI was predictive of longer SSRT only for participants with low to normal trait impulsivity, pointing at a complex interplay between response inhibition, general impulsivity and weight status. Our results support the notion that individuals with obesity do not suffer from diminished response inhibition capacity per se. Rather, the ability to withhold a response depends on context and social norms, and strongly interacts with factors like gender and trait impulsivity.

The analysis of optical wave beams propagation in lens systems

In this paper some aspects of the formation and propagation of optical wave beams in lens systems were considered. As an example, the two-lens optical information processing system was considered. Analysis of the two-lens optical circuit has been made with a systems approach perspective. As part of the radio-optical analogies had been applied certain provisions of the theory of dynamical systems to the spatial optical system. The lens system is represented as a simple series-connected optical elements with known spatial impulse response. General impulse response of such a system has been received, as well as consider some special cases of the impulse response. The question of the relationship between the parameters and the size of the input aperture lenses for undistorted transmission of the optical signal has been considered. Analysis of the energy loss resulting from the finite aperture of the lens. It's based on an assessment of the fraction of radiation that propagates beyond the lens. Analysis showed that the energy losses depend explicitly on the following parameters: radiation wavelength, distance between input aperture and lens, and ratio of the input aperture and lens aperture. With the computer help simulation the dependence of losses was shown on the above parameters

Deterministic impulse control problems: Two discrete approximations of the quasi-variational inequality

In this paper, we study a deterministic infinite horizon, mixed continuous and impulse control problem in Rn, with general impulses, and cost of impulses. We assume that the cost of impulses is a positive function. We prove that the value function of the control problem is the unique viscosity solution of the related first order Hamilton–Jacobi quasi-variational inequality.11QVI. We then propose time discretization schemes of this QVI, where we consider two approximations of the “Hamiltonian hH”, including a natural one. We prove that the approximate value function uh exists, that it is the unique solution of the approximate QVI and that it forms a uniformly bounded and uniformly equicontinuous family. We also prove that the approximate value function converges locally uniformly, towards the value function of the control problem, when the discretization step h goes to zero; the rate of convergence is proved to be in hσ, where 0<σ<1/2.

“Impulsive” suicide attempts: What do we really mean?

Suicide attempts are often regarded as impulsive acts. However, there is little consensus regarding the definition or clinical characteristics of an "impulsive" attempt. To clarify this issue, we examined 3 indicators of the impulsivity of an attempt: (a) preparation, (b) time contemplating the attempt, and (c) self-report that impulsivity motivated the attempt. We examined relationships among the indicators and their relationship to trait impulsivity and characteristics of the suicide attempt. Adult participants (N = 205) with a history of suicide attempts were administered validated interviews and questionnaires. In general, the 3 attempt impulsivity indicators correlated only moderately with each other and not at all with trait impulsivity or with important characteristics of the attempt (e.g., lethality, preattempt communication, motivations). However, there were 2 exceptions. First, intent to die was inversely related to the 3 attempt impulsivity indicators (rs ranged from -.17 to .45) such that more impulsive attempts were associated with lower intent. Second, self-report that the attempt was motivated by impulsivity was related to 3 facets of trait impulsivity (rs ranged from .16 to .41). These findings suggest that individuals endorsing trait impulsivity are likely to describe their attempts as motivated by impulsivity, regardless of the presence of preparation or prolonged contemplation. Overall, study results suggest that the common conception of a unidimensional impulsive attempt may be inaccurate and that the emphasis on general impulsivity in prevention guidelines should be tempered. Implications for suicide risk assessment and prevention are discussed. (PsycINFO Database Record

Delay and probability discounting by drug-dependent cocaine and marijuana users.

Steep discounting of delayed monetary rewards by substance-dependent individuals is well-established. Less is known, however, about discounting other kinds of outcomes, and very little is known about discounting by marijuana-dependent individuals. To determine how cocaine-dependent individuals and marijuana-dependent individuals discount various delayed and probabilistic outcomes, both positive and negative. Marijuana-dependent individuals, cocaine-dependent individuals, and controls performed delay and probability discounting tasks with various hypothetical outcomes. The cocaine-dependent (but not the marijuana-dependent) group discounted delayed liquid rewards and monetary gains, but not delayed losses, more steeply than the control group. In contrast, the marijuana-dependent group (but not the cocaine-dependent group) discounted delayed monetary losses more steeply than controls. There were no group differences in discounting for any of the probabilistic outcomes. Factor analysis revealed a delayed gain factor, a probabilistic gain factor, and a delayed/probabilistic loss factor. The delayed gain factor scores for the cocaine-dependent group, but not the marijuana-dependent group, differed significantly from those of the control group. The groups did not differ in their probabilistic gain factor scores, and the marijuana-dependent group did not differ from the controls with respect to their loss factor scores. These results are inconsistent with the idea that steep discounting of both gains and losses and both delayed and probabilistic outcomes reflects a general impulsivity trait, as well as with the idea that all drug-dependent individuals are steep discounters. Rather, differences in discounting appear to be related to both the type of outcome and the specific drug on which individuals are dependent.

Study of the impulsivity in bipolar parent

Introduction Impulsivity, as defined by Barratt in 1983, is the inability to associate a behavior to context or consequences. It refers to a variety of risky behaviors, inappropriate to the situation and can lead to undesirable consequences. It is well-established that impulsivity is strongly related to bipolar disorder. Currently, we speak of impulsivity trait present even in bipolar patients in euthymia given the hereditary nature of bipolar disorder. In this study, we are interested in assessing impulsiveness in healthy relatives of bipolar patients. Methodology Impulsivity was measured using BARRAT scale [the Barratt impulsiveness Scale-11 (BIS-11)] in 30 healthy subjects who are first degree relatives of bipolar patients treated in Razi hospital; and comparing the results to 30 subjects, witnesses matched for age and sex with no personal or family history of psychiatric disorders. Results The impulsivity score among parents of bipolar patients was significantly higher compared to controls especially for motor impulsivity with average scores 19.15 versus 16.94, respectively. The general impulsivity score among parents of bipolar patients was 61.53±13.83 versus an average score in controls of 47.20±18.26. Limits The small sample size did not allow conclusive results. The difficulties in determining the mental history of the control group (to check the absence of a family history of bipolar disorder).

The relationship between dimensions of impulsivity and alcohol consumption in heavy drinkers

Introduction Impulsivity has been studied as underlying mechanism among addictive disorders such as alcohol use disorder. Several authors have suggested that impulsivity is not a unitary construct and consist of several subconstructs such as response inhibition, risk taking. Objectives This study conceptualized impulsivity as a multidimensional construct and those subconstucts of impulsivity can predict alcohol use differentially. Aims Our aim was to identify the specific component of impulsivity that explained the greatest variance in heavy and problem drinking among a sample of alcohol use disorder. Methods Participants with alcohol use disorder ( n =170) completed a behavioral test battery comprising response inhibition tasks (Stop signal task), the Balloon Analogue Risk Task (BART) as measures of subconstruct of impulsivity. Participants also completed the UPPSP as a measure of general impulsivity. Results In a multiple regression model, impulsivity measured by UPPSP and risk-taking was identified as the measures that predicted alcohol use and problems. Conclusions Results suggest that among patients with alcohol use disorder, a behavioral measure of risk-taking predicts alcohol consumption and alcohol problems, even when individual differences in trait impulsivity are statistically controlled. However, behavioral measures of response inhibition do not predict unique variance in alcohol use in patients with alcohol use disorders.

Impulsivity-focused group intervention to reduce binge eating episodes in patients with binge eating disorder: study protocol of the randomised controlled IMPULS trial

IntroductionThe core symptom of binge eating disorder (BED) is recurrent binge eating that is accompanied by a sense of loss of control. BED is frequently associated with obesity, one of...

Journal Digest

Journal Digest

Competitive devaluations and the trade balance in less developed countries: An empirical study of Latin American countries

Policymakers in less developed countries (LDCs) usually support competitive devaluations to improve the trade balance (TB). In this paper, we estimate the effects of appreciated and depreciated real exchange rates (RER) in the TB of Argentina and Brazil during the period, 1990–2010 using co-integration tests for non-stationary data and vector error correction models (VECM). The estimations confirmed the existence of a long-term relationship among the TB and the RER and foreign and domestic incomes for the countries during opposite RER policies. Based on our estimations, the Marshall–Lerner condition held during periods of more flexible and depreciated RER, and the estimation of the general impulse response functions demonstrated that devaluations in both countries did not follow a J-curve pattern in the short-term.

Business Confidence and Inflation in RSA: Variance Decomposition and General Impulse Response Functions Analysis

The study empirically investigates how business confidence responds to inflation shocks in South Africa using the quarterly time series data spanning the period 1993Q1 – 2013Q1. The study applied the variance decomposition and the Generalized Impulse Response Functions (GIRF) analysis. The variance decomposition revealed that although inflation accounted for about 2 percent in the initial stages, it did account for about 27 percent to shocks in business confidence at later stages. The Generalized Impulse Response Functions (GIRF) also confirmed that inflation uncertainty does cause some negative shocks on how business managers/owners perceive the future of their business prospects. These results show that there is a negative relationship between business confidence and inflation in South Africa. DOI: 10.5901/mjss.2014.v5n16p128

Gender, Self-construal and Impulse Buying Behavior of Young Thai Consumers

The study investigated gender differences in self-construal and impulse buying among young Thai consumers. Contrary to expectations, findings indicated that Thai males were more likely to exhibit general impulse buying and mood management tendencies than females. A subsequent analysis of self-construal among the sample revealed that interdependent self-construals were more likely to report general impulse buying tendencies, while independent self-construals reported significantly higher levels of irresistible urge to buy. These results have broad implications for research and may indicate that global economic upheaval and cultural shifts may have caused traditional role shifts in Thai culture. Marketers must consider these environmental changes and strategize accordingly.

Relationship between Impulsivity, Snack Consumption and Children's Weight

BackgroundChildhood overweight is a public health problem associated with psychosocial and physical problems. Personality traits, such as impulsivity, may contribute to the development of overweight.ObjectiveThis study examines 1) the association between general impulsivity traits (reward sensitivity and disinhibition) and children's weight, 2) the association between impulsivity traits and unhealthy snack consumption, and 3) the potential mediating role of unhealthy snack consumption in the relationship between impulsivity traits and children's weight.MethodsIncluded were 1,377 parent-child dyads participating in the IVO Nutrition and Physical Activity Child cohorT (INPACT). Children had a mean age of 10 years. Parents completed a questionnaire to measure children's unhealthy snack consumption. Children completed a door-opening task to assess reward sensitivity and completed a questionnaire to measure disinhibition. Children's height and weight were measured to calculate their BMI z-scores. Cross-sectional linear regression analyses were performed to test the associations.ResultsDisinhibition was positively associated with unhealthy snack consumption but not with BMI z-scores. Reward sensitivity was not related to unhealthy snack consumption or to BMI z-scores.ConclusionsNo evidence was found for a mediating effect of unhealthy snack consumption in the relation between impulsivity traits and children's weight. However, disinhibition appears to have a negative influence on children's unhealthy snack consumption. Future research focusing on food-related impulsivity in addition to general impulsivity will provide additional insight into factors that influence children's unhealthy snack consumption and weight.

Eating on impulse: the relation between overweight and food-specific inhibitory control.

Consistent with the idea that impulsivity increases vulnerability to temptations of tasty high caloric food, less effective response inhibition is associated with overeating, overweight, and obesity. However, inefficient response inhibition mainly affects eating behavior when strong motivational urges to consume palatable food are simultaneously present. This study, therefore, examined whether overweight is associated specifically with inefficient response inhibition of food-related responses rather than with a general response inhibition deficiency. Eighty-seven female participants (age: M = 26.17, SD = 10.9; body mass index (BMI: kg/m²): M = 22.28, SD = 4.34, range 13.86-39.86) performed both a Stop-Signal task with general stimuli to measure general response inhibition ability, and a Stop-Signal task with food-related pictures to measure ability to inhibit responses to food pictures. As expected, a higher BMI was associated with decreased inhibitory control over food-related responses. There was no association between BMI and general response inhibition. Overweight is not characterized by a general tendency to react impulsively, but instead by impulsive responding toward palatable food. The implication is that weight loss interventions need to focus on decreasing food-specific impulsivity rather than on reducing general impulsivity.

Precursor inter-symbol interference removal by block transmission-based time-reversed equalization

Single-carrier transmission is considered in the general finite impulse response inter-symbol interference (ISI) channel. In an ISI channel with a matched filter, the folded spectrum of the received pulse can be factored into a minimum phase causal part and a maximum phase anticausal part corresponding to the postcursor and precursor ISI, respectively. In this paper, zero-forcing ISI cancellation is considered. In a direct implementation, the precursor equalization is carried out based on truncating and delaying the ideal anticausal precursor equalizer impulse response. In the proposed scheme, a block transmission is adopted, and the precursor equalization is carried out by a time reversal within each block and using a practical minimum phase filter. We show that the ISI can be removed perfectly using the proposed scheme. By means of a numerical example, it is shown that the proposed scheme achieves improved performance compared to the truncate- and delay-based equalizer in terms of transmission rate, delay, and implementation complexity.

Análisis de la impulsividad conductual, cognitiva y planificadora en distintos tipos de adolescentes agresivos

This paper focuses on the study of impulsiveness in a sample of adolescents with different types of aggression. The main research objective was to analyze whether impulsiveness varies between different aggressive adolescents (reactive, proactive and mixed) and non-aggressive ones. Two self-report measures, the Reactive and Proactive Aggression Questionnaire (RPAQ) and the Barratt Impulsiveness Scale (BIS-11) were administrated in a sample recollected in Madrid and composed by 400 adolescents between 12 and 18 years of age (mean = 14.8 and SD = 1.8). The results showed that reactive, proactive and mixed aggressive groups presented higher levels of general impulsiveness than nonaggressive adolescents. No significant differences in relation to cognitive and non-planner dimensions of impulsiveness were found. Nevertheless, motor impulsiveness was higher in reactive, proactive and mixed aggressive adolescents in comparison with non-aggressive ones. These results are discussed pointing out the relevance of motor impulsiveness as a discriminative factor of aggression, particularly in the context of psychological intervention with adolescents in scholar settings

On the solution of general impulse control problems using superharmonic functions

In this paper, a characterization of the solution of impulse control problems in terms of superharmonic functions is given. In a general Markovian framework, the value function of the impulse control problem is shown to be the minimal function in a convex set of superharmonic functions. This characterization also leads to optimal impulse control strategies and can be seen as the corresponding characterization to the description of the value function for optimal stopping problems as a smallest superharmonic majorant of the reward function. The results are illustrated with examples from different fields, including multiple stopping and optimal switching problems.

Predictors of drug use in prison among women convicted of violent crimes

Worldwide, some prisoners consume illicit drugs while in prison. There is now some recognition of risk factors for this among male but not female prisoners. The aim was to identify variables associated with drug use by women in prison after conviction for violent crimes. Data were obtained from 315 women serving a sentence for robbery or homicide in the Penitentiary of Sant'Ana, São Paulo State, Brazil. Mainly self-report assessments of alcohol and drug misuse, sexual and general impulsiveness, depression, and psychosocial and criminological features were completed. Data were analysed using descriptive statistics and multivariate logistic regression. Thirty-five (11%) women reported illicit drug use in prison. Younger age, history of childhood sexual abuse, having committed robbery (rather than homicide), earlier onset of criminal activities, higher scores on sexual impulsiveness, drug-related problems prior to incarceration and having same-sex relationships inside prison were associated with a higher risk of using drugs in prison. In a multiple logistic regression, only prior drug history and having same-sex relationships in prison were independently associated with in-prison drug use. Illicit drug use in prison impairs rehabilitative goals. Identification of risk factors for this can help to recognise people with high treatment needs. We found that in-prison drug users seemed to be an exceptionally needy group, likely to have more wide ranging historical problems than their similar offending peers. It is essential to check for history of drug use outside prison. The strong association with active sexual behaviour in the prison highlighted another area of vulnerability, requiring sensitive in-prison attention to safeguard these women. Further research to understand the reasons for this relationship is recommended.

Multidimensionality in Impulsivity and Alcohol Use: A Meta-Analysis Using the UPPS Model of Impulsivity

Although there is considerable support for the relationship between impulsivity and alcohol use, the use of multidimensional conceptualizations of impulsivity and alcohol use has lead to varying relationship sizes across studies. The aims of the current meta-analysis are to (i) examine variability in the magnitude of the bivariate relationship between impulsivity and alcohol use across studies and (ii) describe the pattern of effects between specific impulsivity traits and alcohol use variables, using the UPPS model of impulsivity. Ninety-six studies were meta-analyzed using a random effects model to examine the relationship between general impulsivity and alcohol use, as well as the relationships among separate impulsivity traits based in the UPPS model of impulsivity and specific alcohol use outcomes. Results indicate that, in general, impulsivity and alcohol use are related (r = 0.28); however, this effect size varied significantly across studies (from -0.05 to 1.02). Drinking quantity was most strongly predicted by lack of perseverance (r = 0.32), whereas all traits equally predicted drinking frequency. Drinking problems were most highly related to negative (r = 0.35) and positive (r = 0.34) urgency, and alcohol dependence was most highly related to negative urgency (r = 0.38) and lack of planning (r = 0.37). Effect sizes between impulsivity and alcohol use vary significantly by UPPS trait used in each study; thus, findings suggest and further reinforce the view in the literature that specific impulsivity-related constructs differentially relate to specific alcohol use outcomes.

Signal detection in pathological skin picking. Findings from non – clinical sample

Aim of the studyThe present study investigated the role of general impulsivity in pathological skin picking (PSP).Subject or material and methodsThree groups of participants: university students who pick their skin and experience distress and/or functional impairment caused by picking (n = 27), students who pick their skin but do not experience distress and/or functional impairment caused by picking (n = 19), and students without history of skin picking (n = 43) were administered the task based on the search for the emotionally neutral signal hidden among distractors. It was predicted that individuals suffering from PSP should present an impulsive reaction style, i.e. they should search for the signal faster than individuals without history of PSP and should react to irrelevant stimuli rather than missing the correct reaction.ResultsParticipants with severe picking performed as quickly and correctly as controls, thus not revealing an impulsive reaction pattern. Students with milder forms of picking reacted more slowly than the others gradually diminishing their performance as the task was extended.DiscussionIndividuals with severe PSP symptoms are not characterized by general impulsiveness defined as a tendency to react quickly and carelessly. Skin picking behaviors of different severity may be associated with different signal detection patterns.ConclusionsThe results of the current study indicate that skin picking is not a homogeneous condition. They also provide that skin picking behavior in ‘severe’ pickers and non – ‘severe’ ones may have different underlying psychological mechanisms.