Desensitization Hypothesis Research Articles

Violent Video Games and the P300: No Evidence to Support the Neural Desensitization Hypothesis.

It has been proposed that exposure to violent video games (VVGs) resulted in alterations of social behaviors such as increased aggression. The most damaging reported effect of playing VVGs is neural desensitization to violent stimuli and this is a major concern given the reported number of players and time spent playing major video game titles. The aim of this study was to investigate the existence of neural desensitization that was reported at the P300 component of event-related potentials (ERPs) in response to violent stimuli. Eighty-seven participants were recruited and placed into one of two conditions based on their video gaming behavior (violent games players and nonplayers). ERPs were recorded from participants who passively viewed violent and neutral images selected from the International Affective Picture System (IAPS). The participants then played a VVG, postplaying ERPs were recorded while viewing the neutral and violent IAPS images. The mean amplitudes of the P300 were analyzed with respect to condition, time, and content. There was a significant effect of image but not of VVG player and nonplayer. The results were interpreted as evidence against the neural desensitization hypothesis. The findings of this study are consistent with imaging research and the implications for the reported negative effects of playing VVGs are discussed.

Racial and Ethnic Comparison of Ecological Risk Factors and Youth Outcomes: A Test of the Desensitization Hypothesis

Minority youth, because of structural, ecological, and societal inequalities, are at heightened risk of reporting depression and experiencing negative sanctions associated with delinquency. Sociological theories suggest that greater exposure to ecological risk factors at the peer, family, school and community levels are associated with elevated rates of youth depression and delinquency. Desensitization theory posits that repeated exposures to ongoing stressors result in a numbing of psychological and behavioral responses. Thus, it remains unclear whether racial/ethnic differences exist with regards to how contextual stressors correlate with depression and delinquency. Using a sample of 616 Black, 687 Latinx, and 1,318 White youth, this study explores racial/ethnic differences across four ecological risk factors of risky peers, low family warmth, poor school engagement, and community violence as they relate to youth delinquency and depression. Data were collected through in-school survey of youth from 16 public schools surrounding a major city in the Midwest. Significant racial/ethnic differences provided partial support for the desensitization theory. Among Black youth, the magnitude of relationships between ecological risk factors and delinquency was significantly weaker for three of the four predictors and for all four predictors of depression in comparison to White youth. Among Latinx youth, the magnitude of relationships between ecological risk factors was significantly weaker for depression, but not delinquency, in comparison to White youth. Results indicate that ecological risk factors may have differential associations to youth depression and delinquency, which may call for culturally tailored intervention approaches.

Risk perception: A study using dashcam videos and participants from different world regions

Objective: Research has shown that perceived risk is a vital variable in the understanding of road traffic safety. Having experience in a particular traffic environment can be expected to affect perceived risk. More specifically, drivers may readily recognize traffic hazards when driving in their own world region, resulting in high perceived risk (the expertise hypothesis). Oppositely, drivers may be desensitized to traffic hazards that are common in their own world region, resulting in low perceived risk (the desensitization hypothesis). This study investigated whether participants experienced higher or lower perceived risk for traffic situations from their region compared to traffic situations from other regions. Methods: In a crowdsourcing experiment, participants viewed dashcam videos from four regions: India, Venezuela, United States, and Western Europe. Participants had to press a key when they felt the situation was risky. Results: Data were obtained from 800 participants, with 52 participants from India, 75 from Venezuela, 79 from the United States, 32 from Western Europe, and 562 from other countries. The results provide support for the desensitization hypothesis. For example, participants from India perceived low risk for hazards (e.g., a stationary car on the highway) that were perceived as risky by participants from other regions. At the same time, support for the expertise hypothesis was obtained, as participants in some cases detected hazards that were specific to their own region (e.g., participants from Venezuela detected inconspicuous roadworks in a Venezuelan city better than did participants from other regions). Conclusion: We found support for the desensitization hypothesis and the expertise hypothesis. These findings have implications for cross-cultural hazard perception research.

Crying Wolf or Ever Vigilant: Do Wide-Ranging Product Warnings Increase or Decrease Sensitivity to Other Product Warnings?

Product safety warnings are pervasive in the marketplace. The frequency and, in some cases, content of such warnings has led some to speculate that the cumulative effects may undermine the efficacy of warnings in general—including that of different warnings for other products. According to the generalized desensitization hypothesis, numerous past warnings can cause consumers to react less strongly to safety warnings for other products subsequently encountered. In contrast, the literature on goal activation and compensatory consumer behavior suggests that any self-protective goals aroused by initial warnings can potentially generalize to increase awareness and safety precautions in other warning contexts, consistent with the generalized sensitization hypothesis. The authors tested both hypotheses by manipulating the number and strength of an initial set of product warnings and examining whether such exposure generalized to different product warnings. In support of the generalized sensitization prediction, prior warnings motivated appreciation of the risks communicated in a different warning context and increased relevant safety behaviors. These generalized sensitization effects were moderated by self-affirmation, supporting the prediction that they are driven by self-protective goals.

Delayed Antidepressant Efficacy and the Desensitization Hypothesis.

Many conventional antidepressants can quickly raise the levels of extracellular serotonin, yet their positive effects on mood ensues only weeks later. This delay in efficacy is a clinical problem that has proven difficult to overcome. Early investigation noted that the initial increases in extracellular serotonin engaged strong feedback inhibition of serotonin neurons via 5-HT1A autoreceptors, resulting in a profound reduction in their firing rate. Over the course of chronic treatment, however, firing rate returned to normal and the inhibition via 5-HT1A receptor agonists was attenuated. The coincident timeline of these phenomena led to the influential hypothesis that the relationship was causal and that gradual loss of feedback inhibition mediated by 5-HT1A receptors was critical to the delayed therapeutic onset. Simple and appealing, the desensitization hypothesis has taken strong hold, yet much of the supporting evidence is circumstantial and there are several observations that would refute a causal relationship. In particular, even though 5-HT1A receptors may desensitize, there is evidence that feedback inhibition mediated by remaining receptors persists. That is, baseline serotonin firing rate returns to normal not because of 5-HT1A desensitization but rather despite ongoing feedback inhibition. Thus, while 5-HT1A receptors remain important for emotional behavior, it may be other slow-adaptive changes triggered by antidepressants that allow for therapeutic effects, such as those involving glutamatergic synaptic plasticity.

Effects of workload, work complexity, and repeated alerts on alert fatigue in a clinical decision support system

BackgroundAlthough alert fatigue is blamed for high override rates in contemporary clinical decision support systems, the concept of alert fatigue is poorly defined. We tested hypotheses arising from two possible alert fatigue mechanisms: (A) cognitive overload associated with amount of work, complexity of work, and effort distinguishing informative from uninformative alerts, and (B) desensitization from repeated exposure to the same alert over time.MethodsRetrospective cohort study using electronic health record data (both drug alerts and clinical practice reminders) from January 2010 through June 2013 from 112 ambulatory primary care clinicians. The cognitive overload hypotheses were that alert acceptance would be lower with higher workload (number of encounters, number of patients), higher work complexity (patient comorbidity, alerts per encounter), and more alerts low in informational value (repeated alerts for the same patient in the same year). The desensitization hypothesis was that, for newly deployed alerts, acceptance rates would decline after an initial peak.ResultsOn average, one-quarter of drug alerts received by a primary care clinician, and one-third of clinical reminders, were repeats for the same patient within the same year. Alert acceptance was associated with work complexity and repeated alerts, but not with the amount of work. Likelihood of reminder acceptance dropped by 30% for each additional reminder received per encounter, and by 10% for each five percentage point increase in proportion of repeated reminders. The newly deployed reminders did not show a pattern of declining response rates over time, which would have been consistent with desensitization. Interestingly, nurse practitioners were 4 times as likely to accept drug alerts as physicians.ConclusionsClinicians became less likely to accept alerts as they received more of them, particularly more repeated alerts. There was no evidence of an effect of workload per se, or of desensitization over time for a newly deployed alert. Reducing within-patient repeats may be a promising target for reducing alert overrides and alert fatigue.

Lack of Evidence That Neural Empathic Responses Are Blunted in Excessive Users of Violent Video Games: An fMRI Study.

The use of violent video games has been often linked to increase of aggressive behavior. According to the General Aggression Model, one of the central mechanisms for this aggressiveness inducing impact is an emotional desensitization process resulting from long lasting repeated violent game playing. This desensitization should evidence itself in a lack of empathy. Recent research has focused primarily on acute, short term impact of violent media use but only little is known about long term effects. In this study 15 excessive users of violent games and control subjects matched for age and education viewed pictures depicting emotional and neutral situations with and without social interaction while fMRI activations were obtained. While the typical pattern of activations for empathy and theory of mind networks was seen, both groups showed no differences in brain responses. We interpret our results as evidence against the desensitization hypothesis and suggest that the impact of violent media on emotional processing may be rather acute and short-lived.

Personality factors predict spicy food liking and intake

A number of factors likely affect the liking of capsaicin-containing foods such as social influences, repeated exposure to capsaicin, physiological differences in chemosensation, and personality. For example, it is well known that repeated exposure to capsaicin and chilies can result in chronic desensitization. Here, we explore the relationship between multiple personality variables – body awareness/consciousness, sensation seeking, and sensitivity to punishment, and sensitivity to reward – and the liking and consumption of capsaicin-containing foods. As expected, a strong relationship was found between liking of spicy foods and frequency of chili consumption. However, no association was observed between frequency of chili consumption and the perceived burn/sting of sampled capsaicin. Nor was there any association between perceived burn/sting of capsaicin and any of the personality measures. Private Body Consciousness did not relate to any of the measures used in the current study. Sensation Seeking showed positive correlations with the liking of spicy foods, but not non-spicy control foods. Sensitivity to Punishment showed no relation with frequency of chili consumption, and nonsignificant negative trends with liking of spicy foods. Conversely, Sensitivity to Reward was weakly though significantly correlated with the liking of a spicy meal, and similar nonsignificant trends were seen for other spicy foods. Frequency of chili consumption was positively associated with Sensation Seeking and Sensitivity to Reward. Present data indicate individuals who enjoy spicy foods exhibit higher Sensation Seeking and Sensitivity to Reward traits. Rather than merely showing reduced response to the irritating qualities of capsaicin as might be expected under the chronic desensitization hypothesis, these findings support the hypothesis that personality differences may drive differences in spicy food liking and intake.

Chronic exposure to violent video games is not associated with alterations of emotional memory

AbstractAlthough acute effects of violent video game (VVG) exposure on affect and behaviour have been studied extensively, less is known about VVG effects on cognition. The present study examined whether chronic exposure to VVGs was associated with alterations in emotional long‐term memory. Participants completed an old‐new recognition task with 300 pictures of scenes ranging in emotion (negative, neutral and positive). We analysed accuracy and reaction time data using diffusion modelling to test a desensitization hypothesis. According to this hypothesis, VVG players would show reduced memory or a less liberal response bias for negative stimuli, compared with nonplayers. Contrary to the desensitization hypothesis, VVG exposure was not associated with differences in memory or response bias. This result suggests that, unlike other cognitive domains, long‐term memory may be robust to deleterious influences of chronic VVG exposure. Copyright © 2010 John Wiley & Sons, Ltd.

Duration as a phonetic cue in the categorization of /i:/‐/ɪ/ and /s/‐/z/ by spanish/Catalan learners of English.

Previous research has shown that Spanish/Catalan learners of English (SCLs) rely on duration rather than spectral cues in the categorization of contrastive English vowel pairs such as /i:‐/ɪ/, despite length being nondistinctive in Spanish/Catalan. Native English speakers (NESs) rely more heavily on V‐C duration ratio than on glottal pulsing in the perception of voicing contrasts in ‐VC contexts. This study investigated whether SCLs’ overreliance on duration in vowel categorization also applied to consonants in contexts (‐VC) where lack of closure voicing makes duration the main cue to voicing for NESs. SCLs (N=40) and NESs (N=15) participated in two lexical decision tasks consisting of /f/+V+/t/ stimuli drawn from two 8‐step continua with shortened (/i:/) and lengthened (/ɪ/) vowels; and /p/+/i:/+C stimuli drawn from six 8‐step continua with simultaneously and independently modified vowels and final consonants (/i:s/‐/i:z/). Manipulating duration had a significant effect on SCLs’ categorization of /i:/ and /ɪ/, but not on SCLs’ categorization of /s/ and /z/, suggesting that SCLs made use of duration as a cue to vowel categorization, but did not use duration as a cue to voicing. These results are interpreted and further discussed in light of Bohn’s Desensitization Hypothesis and McAllister’s Feature Hypothesis.

Violent Content Enhances Video Game Performance

This study assesses the impact of violent video game content on players’ game performance. According to the desensitization hypothesis ( Carnagey, Anderson, & Bushman, 2007 ), violent content may elicit negative affective responses and inhibitions, which in turn should interfere with performance. On the other hand, the players might understand virtual violent acts as a digital form of rough-and-tumble play, associated with positive emotions and mobilization, which in turn should raise performance. To test these competing hypotheses on game performance, N = 50 males with no prior violent gaming experience were exposed to three different versions of a custom-made video game in which the actions to be performed were identical, though they were audio-visually presented to appear either nonviolent, moderately, or extremely violent. The results show no indication of an initial inhibition of aggressive behavior, that is, performance is elevated and remains so if the action is presented audio-visually as being violent. This supports the notion that being involved in violent video game activity is perceived as an essentially harmless acting-out of playful fighting behavior.

Tolerance to Repeated Morphine Administration Is Associated with Increased Potency of Opioid Agonists

Tolerance to the pain-relieving effects of opiates limits their clinical use. Although morphine tolerance is associated with desensitization of mu-opioid receptors, the underlying cellular mechanisms are not understood. One problem with the desensitization hypothesis is that acute morphine does not readily desensitize mu-opioid receptors in many cell types. Given that neurons in the periaqueductal gray (PAG) contribute to morphine antinociception and tolerance, an understanding of desensitization in PAG neurons is particularly relevant. Opioid activity in the PAG can be monitored with activation of G-protein-mediated inwardly rectifying potassium (GIRK) currents. The present data show that opioids have a biphasic effect on GIRK currents in morphine tolerant rats. Opioid activation of GIRK currents is initially potentiated in morphine (EC(50)=281 nM) compared to saline (EC(50)=8.8 microM) pretreated rats as indicated by a leftward shift in the concentration-response curve for met-enkephalin (ME)-induced currents. These currents were inhibited by superfusion of the mu-opioid receptor antagonist beta-funaltrexamine (beta-FNA) suggesting that repeated morphine administration enhances agonist stimulation of mu-opioid receptor coupling to G-proteins. Although supersensitivity of mu-opioid receptors in the PAG is counterintuitive to the development of tolerance, peak GIRK currents from tolerant rats desensitized more than currents from saline pretreated rats (56% of peak current after 10 min compared to 15%, respectively). These data indicate that antinociceptive tolerance may be triggered by enhanced agonist potency resulting in increased desensitization of mu-opioid receptors.

Do urban adolescents become desensitized to community violence? Data from a national survey.

This study explored whether the response of urban adolescents to community violence exposure differs from their response to family violence and sexual assault. More specifically, the authors explored whether desensitization to community violence exposure was more common compared with desensitization to other violence-related stressors. Participants included 1,245 urban adolescents drawn from a national probability sample of 4,023 youth (aged 12-17 years) who were interviewed about their history of interpersonal violence exposure, symptoms of posttraumatic stress disorder (PTSD), and delinquency. A negative curvilinear effect of community violence exposure on PTSD combined with a positive linear effect of exposure on delinquency was considered evidence for desensitization. Results provided minimal support for the desensitization hypothesis and revealed increasing levels of PTSD symptoms and delinquent behaviors among boys and girls exposed to higher levels of all three violence types.

The endocrinology of sexual arousal

The relevance of testosterone, oestradiol and certain peptides (oxytocin (OT), beta-endorphin and prolactin (PRL)) to sexual arousal in humans is reviewed. In addition to behavioural studies, evidence of distribution of gonadal steroid receptors in the brain and the limited evidence from brain imaging are also considered. Testosterone plays a key role in the adult male, with clear, consistent evidence from studies of hypogonadal and eugonadal men. The roles of testosterone in the development of sexual arousability, and in the aging male, are less clear. The relevance of aromatization and of non-sexual effects of testosterone which might indirectly influence sexual arousal are not well understood. Testosterone in the female presents a more complex, less consistent picture. One possible explanation is a much greater variability across women in responsiveness to testosterone. A 'desensitization hypothesis' to account for the striking gender differences is offered. There is limited evidence of a direct effect of oestradiol on sexual arousability in women. The extent to which testosterone in women acts by conversion to oestradiol or by increase of free oestradiol is not yet clear. The role of peptides in sexual arousal remains uncertain, partly because of the multiple roles and sites of action of most peptides. OT and beta-endorphin appear to have both excitatory and inhibitory effects. PRL has been proposed as an inhibitory factor via direct inhibition of dopaminergic activity, but the evidence for this is inconclusive. Whereas the traditional concept of 'hormone' continues to apply to the role of testosterone and oestradiol in sexual arousal, peptides present a more complex role.

Greek perception and production of an English vowel contrast: A preliminary study

This study focused on language-independent principles functioning in acquisition of second language (L2) contrasts. Specifically, it tested Bohn’s Desensitization Hypothesis [in Speech perception and linguistic experience: Issues in Cross Language Research, edited by W. Strange (York Press, Baltimore, 1995)] which predicted that Greek speakers of English as an L2 would base their perceptual identification of English /i/ and /I/ on durational differences. Synthetic vowels differing orthogonally in duration and spectrum between the /i/ and /I/ endpoints served as stimuli for a forced-choice identification test. To assess L2 proficiency and to evaluate the possibility of cross-language category assimilation, productions of English /i/, /I/, and /ε/ and of Greek /i/ and /e/ were elicited and analyzed acoustically. The L2 utterances were also rated for the degree of foreign accent. Two native speakers of Modern Greek with low and 2 with intermediate experience in English participated. Six native English (NE) listeners and 6 NE speakers tested in an earlier study constituted the control groups. Heterogeneous perceptual behavior was observed for the L2 subjects. It is concluded that until acquisition in completely naturalistic settings is tested, possible interference of formally induced meta-linguistic differentiation between a ‘‘short’’ and a ‘‘long’’ vowel cannot be eliminated.

Perception of the English tense/lax vowel contrast by native speakers of Russian

The present study examined the effect of native language background on the perception of American English tense and lax front unrounded vowels ([i] and [I]). These vowels are distinguishable according to both spectral (vowel quality) and temporal (vowel duration) properties. Nineteen native Russian and 12 native American English listeners identified stimuli from a two-dimensional beat-bit continuum varying in 10 spectral and nine duration steps. English listeners used predominantly spectral quality when identifying these vowels, but also showed some reliance on duration cues. In contrast, Russian listeners failed to employ vowel quality to differentiate English tense and lax vowels which can be explained by their assimilation to the same Russian /i/ phoneme in a ‘‘single category assimilation’’ process (Best, 1995). Instead, they relied almost entirely on the duration cue, despite the absence of distinctive vowel length in Russian. These results could be interpreted as supporting the desensitization hypothesis (Bohn, 1995): When spectral differences are insufficient to distinguish a non-native vowel contrast, duration will be employed by default. Alternatively, the strength of Russian listeners’ reliance on duration may instead reflect the influence of prior experience with subphonemic duration contrasts within the lexical stress system of the Russian language.

The augmentation hypothesis for improvement of antidepressant therapy: is pindolol a suitable candidate for testing the ability of 5HT1A receptor antagonists to enhance SSRI efficacy and onset latency?

The development of selective serotonin reuptake inhibitors (SSRIs) provided a major advancement in the treatment of depression. However, these drugs suffer from a variety of drawbacks, most notably a delay in the onset of efficacy. One hypothesis suggests that this delay in efficacy is due to a paradoxical decrease in serotonergic (5-HT) neuronal impulse flow and release, following activation of inhibitory presynaptic 5-HT1A autoreceptors, following acute administration of SSRIs. According to the hypothesis, efficacy is seen only when this impulse flow is restored following desensitization of 5-HT1A autoreceptors and coincident increases in postsynaptic 5-HT levels are achieved. Clinical proof of this principal has been suggested in studies that found a significant augmenting effect when the beta-adrenergic/5-HT1A receptor antagonist, pindolol, was coadministered with SSRI treatment. In this article, we review preclinical electrophysiological and microdialysis studies that have examined this desensitization hypothesis. We further discuss clinical studies that utilized pindolol as a test of this hypothesis in depressed patients and examine preclinical studies that challenge the notion that the beneficial effect of pindolol is due to functional antagonism of the 5-HT1A autoreceptors.

Neutralisation as a Process of Graduated Desensitisation: Moral Values of Offenders

This study explored neutralization as a process of graduated desensitization, providing a theoretical link between the opposing tenets of neutralisation theory and the subcultural theory of criminal behaviour Participants were 95 adult male offenders who were categorised according to type of offence (personal or property) and level of offending involvement (low or high). Offenders' excuse acceptance and offence approval were examined for S offence situations. The results indicated offenders' excuse acceptance varied as a function of their level of involvement in crime. Specifically, for property offence situations, low-involvement property offenders reported higher excuse acceptance than did high-involvement property offenders, whereas for personal offence situations, low-involvement personal offenders reported higher excuse acceptance than did high-involvement personal offenders. This finding partially supported the graduated desensitization hypothesis, providing an empirical link between neutralisation and the subcultural theory of criminal behaviour

Hypoxia-induced downregulation of beta-adrenergic receptors in rat heart.

To test the desensitization hypothesis of cardiac beta-adrenergic receptors (beta-AR) in chronic hypoxia, the effect of 1, 3, 7, 15, and 21 days of exposure to hypobaric hypoxia (380 Torr) was evaluated in Wistar rats. Exposure to hypoxia for 1-15 days did not induce any change in right and left ventricular beta-AR density (Bmax) determined with [125I]iodocyanopindolol or in antagonist affinity. After 21 days, Bmax decreased by 24% in the left ventricle. In contrast, no change in beta-AR was shown in the right hypertrophied ventricle. Agonist affinity in the left ventricle was not altered, as shown by the analysis of displacement curves of isoproterenol (normoxia 185 +/- 26 nM, hypoxia 170 +/- 11 nM). Moreover, there was no significant decrease in adenylate cyclase activity (pmol.mg-1.min-1) in the left ventricle. In the right ventricle, a 21-day exposure to hypoxia led to a decrease in basal and maximal activity when stimulated by isoproterenol. A decrease in tissue norepinephrine content was observed after 7 days of hypoxia. In conclusion, these data support the beta-AR downregulation hypothesis as one of the mechanisms of myocardial adaptation to high altitude occurring after 2-3 wk of exposure to hypoxia. The regulation pathways of beta-AR may differ between left nonhypertrophied and right hypertrophied ventricles. No evidence of profound abnormality of signal transduction was shown.

Attitudes toward death: a desensitization hypothesis.

Attitudes toward death is a subject largely overlooked by psychology. This article reports on the development of a Likert-type scale measuring attitude toward death. Item analysis produced 32 items, with a corrected split-half reliability coefficient of .92. The scale did not predict differences between donors and professors and did not relate to age, sex, or self-esteem. It did, however, correlate negatively with religiosity, level of education, and positively with exposure to deaths of non-intimate persons. The results suggest that positive attitudes toward death are indicated by a non-religious outlook, low investment in self-relevant goals, and exposure to non-intimate (and less traumatic) deaths.