Affective Habituation Research Articles

Effects of desensitization on odors varying in concentration and pleasantness

AbstractBackgroundDesensitization in response to repetitive odorous stimulations is a common and well‐investigated process, but it has been a matter of discussion in which way this process relates to odor valence. Our goal was to investigate changes of intensity and pleasantness induced by desensitization in odors in relation to their valence and concentration.Materials and MethodsUsing air‐dilution olfactometry, 30 normosmic participants received two pleasant (phenylethylalcohol [PEA], mixture of pleasant odorants [mix‐P]) and two unpleasant odors (hydrogen sulfide [H2S], mixture of unpleasant odorants [mix‐NP]). At the baseline (before desensitization), four different concentrations of each odor were presented randomly for 0.2 s, with 40 s inter‐stimulus interval. During the desensitization procedure, the odor used was presented continuously for 15 s. Following an odor‐free interval of 4 s the same odor was presented again, in the post‐desensitization phase. Odor intensity and pleasantness were rated after presenting each stimulus in pre and post desensitization phases.ResultsAt baseline, Mix‐P was rated as pleasant and H2S was rated as unpleasant, as expected, while PEA and mix‐NP were rated as slightly pleasant or neutral, respectively. For intensity, desensitization was found for all odors regardless of hedonic tone, with the effect being more pronounced with PEA and mix‐NP at lower concentrations. A decrease of pleasantness/unpleasantness (“affective habituation”) was present for the two lower concentrations of the pleasant mixture, while hedonic ratings of the unpleasant odors remained largely unchanged.ConclusionsThese results suggest that, in this model, desensitization in intensity between pleasant and unpleasant odors was similar and affective habituation only occurred for the most pleasant odor.Practical ApplicationsOur study unraveled the link between odor desensitization and valence considering the concentration effect, where the intensity was decreased for the relatively “neutral” odors and pleasantness was habituated only for the pleasant odor. These results help to explain individual differences in the effects of olfactory loss and provide a promising perspective for personalized treatment for olfactory loss in clinics, for instance, fast adaptation and parosmia.

Sleep fails to depotentiate amygdala-reactivity to negative emotional stimuli in youth with elevated symptoms of anxiety.

Sleep-related problems often precede escalating anxiety in early adolescence. Pushing beyond broad sleep-mental health associations and toward mechanistic theories of their interplay can inform etiological models of psychopathology. Recent studies suggest that sleep depotentiates neural (e.g., amygdala) reactivity during reexposure to negative emotional stimuli in adults. Persistent amygdala reactivity to negative experiences and poor sleep characterize anxiety, particularly at the transition to adolescence. We propose that sleep depotentiates amygdala reactivity in youth but fails to do so among youth with anxiety. Participants (n = 34; 18 males; age, mean [M] = 11.35, standard deviation [SD] = 2.00) recruited from the community and specialty anxiety clinics viewed valenced images (positive, negative, and neutral) across two fMRI sessions (Study, Test), separated by a 10-12-hour retention period of sleep or wake (randomized). Mixed linear models regressed basolateral amygdala (BLA) activation and BLA-medial prefrontal cortex (mPFC) functional connectivity to negative images on Time, Condition, and Anxiety Severity. There were greater reductions in BLA activations to negative target images from Study to Test in the Sleep Condition, which was blunted with higher anxiety (b = -0.065, z = -2.355, p = 0.019). No such sleep- or anxiety-related effects were observed for BLA-mPFC functional connectivity (ps > 0.05). Sleep supports depotentiation of amygdala reactivity to negative stimuli in youth, but this effect is blunted at higher levels of anxiety. Disruptions in sleep-related affective habituation may be a critical, modifiable driver of anxiety.

Self-Conscious Affect Is Modulated by Rapid Eye Movement Sleep but Not by Targeted Memory Reactivation–A Pilot Study

The neurophysiological properties of rapid eye movement sleep (REMS) are believed to tune down stressor-related emotional responses. While prior experimental findings are controversial, evidence suggests that affective habituation is hindered if REMS is fragmented. To elucidate the topic, we evoked self-conscious negative affect in the participants (N = 32) by exposing them to their own out-of-tune singing in the evening. Affective response to the stressor was measured with skin conductance response and subjectively reported embarrassment. To address possible inter-individual variance toward the stressor, we measured the shame-proneness of participants with an established questionnaire. The stressor was paired with a sound cue to pilot a targeted memory reactivation (TMR) protocol during the subsequent night's sleep. The sample was divided into three conditions: control (no TMR), TMR during slow-wave sleep, and TMR during REMS. We found that pre- to post-sleep change in affective response was not influenced by TMR. However, REMS percentage was associated negatively with overnight skin conductance response habituation, especially in those individuals whose REMS was fragmented. Moreover, shame-proneness interacted with REM fragmentation such that the higher the shame-proneness, the more the affective habituation was dependent on non-fragmented REMS. In summary, the potential of REMS in affective processing may depend on the quality of REMS as well as on individual vulnerability toward the stressor type.

Sleep and emotion processing in paediatric posttraumatic stress disorder: A pilot investigation.

SummaryEmotion processing abnormalities and sleep pathology are central to the phenomenology of paediatric posttraumatic stress disorder, and sleep disturbance has been linked to the development, maintenance and severity of the disorder. Given emerging evidence indicating a role for sleep in emotional brain function, it has been proposed that dysfunctional processing of emotional experiences during sleep may play a significant role in affective disorders, including posttraumatic stress disorder. Here we sought to examine the relationship between sleep and emotion processing in typically developing youth, and youth with a diagnosis of posttraumatic stress disorder . We use high‐density electroencephalogram to compare baseline sleep with sleep following performance on a task designed to assess both memory for and reactivity to negative and neutral imagery in 10 youths with posttraumatic stress disorder, and 10 age‐ and sex‐matched non‐traumatized typically developing youths. Subjective ratings of arousal to negative imagery (ΔArousal = post‐sleep minus pre‐sleep arousal ratings) remain unchanged in youth with posttraumatic stress disorder following sleep (mean increase 0.15, CI −0.28 to +0.58), but decreased in TD youth (mean decrease −1.0, 95% CI −1.44 to −0.58). ΔArousal, or affective habituation, was negatively correlated with global change in slow‐wave activity power (ρ = −0.58, p = .008). When considered topographically, the correlation between Δslow‐wave activity power and affective habituation was most significant in a frontal cluster of 27 electrodes (Spearman, ρ = −0.51, p = .021). Our results highlight the importance of slow‐wave sleep for adaptive emotional processing in youth, and have implications for symptom persistence in paediatric posttraumatic stress disorder. Impairments in slow‐wave activity may represent a modifiable risk factor in paediatric posttraumatic stress disorder.

Dynamics of Affective Habituation to Touch Differ on the Group and Individual Level

Slow stroking touch activates C-tactile (CT) fibres in the human skin and is typically described as pleasant. Over a longer duration of stroking, affective habituation sets in, indicated by a reduction in rated pleasantness. However, it is not clear whether the group level effect is represented on an individual level. We analyse the stability of individual ratings of slow stroking touch and their relationship to behavioural and physiological measures.Forty-eight participants (23 women) were repeatedly stroked with a velocity maximally activating CT fibres. The perceived pleasantness was rated on a visual analogue scale. In order to examine the stability of pleasantness ratings, the experiment was repeated after a couple of days. During the experiment, electrocardiogram (ECG) and facial-electromyography (EMG) data were recorded.On the group-level, previous results of affective habituation to touch were replicated and stable across sessions. On the individual level, however, less than half of the participants showed a significant reduction of pleasantness in the course of the experiment. Moreover, the remaining participants showed either no change, random rating behaviour or even an increase in pleasantness ratings during the course of the experiment.The individual response patterns were variable across sessions but stable above the chance level. Furthermore, the response patterns could not be explicitly associated with any of the behavioural or physiological measures. Our findings indicate a lack of group-to-individual generalizability for affective habituation to touch. The variability of rating patterns over time indicates that they are not conclusively determined by stable individual characteristics. Future research investigating touch should favour a more individual approach to the more commonly applied group analysis.

Re-Living Suspense: Emotional and Cognitive Responses During Repeated Exposure to Suspenseful Film.

Arguments about the effects of repeated exposure to a suspenseful narrative raise controversial disputes over the paradox of suspense. The lexical meaning and the theoretical analyses of suspense imply that suspense cannot be experienced repeatedly because, in such cases, the knowledge from prior viewings and the resolution of outcome will eliminate tension and suspense. However, previous studies have argued that suspense can be re-experienced even when the participants know the outcome or repeatedly confront a suspenseful narrative. This study investigated the effects of repeated exposure to a suspenseful film by collecting self-reported questionnaires and measuring psychophysiological responses. The participants (N = 50) watched clips of a suspenseful film three times and answered self-reported items regarding suspense, arousal, and enjoyment. Psychophysiological data, including skin conductance level (SCL) and electrocardiogram (ECG), were collected while the participants watched the video clips. It was hypothesized that self-reported suspense, arousal, and enjoyment as well as the physiological indices of arousal (SCL) and attention (ECG) would decrease upon repeated viewing of suspenseful clips. Furthermore, it was postulated that there would be inter-group differences depending on the awareness of potential or definite change in outcome at the end of repeatedly shown suspenseful events. The results showed that self-reported suspense and arousal, as well as the physiological measures of SCL, declined with repeated exposure, although there were no significant differences on self-reported enjoyment. No group difference was found in self-reported items, but meaningful significant changes were observed in the group comparison of SCL and ECG. The findings suggest that repeated exposure to suspenseful films could result in affective habituation or desensitization to repeated stimuli. The implications and the limitations of the current study and suggestions for future research are discussed.

The interplay between attention and long-term memory in affective habituation.

Previous studies have consistently shown that repeated exposure to emotional stimuli leads to a reduction in cortical and autonomic responses (affective habituation). These findings emerge from studies conducted within a single experimental session, preventing the possibility of disentangling short-term from long-term habituation effects. The present study investigated whether affective habituation reflects a short-living learning process, or a more stable change involving long-term memory. Participants went through a first habituation phase consisting of 80 repetitions of the same set of emotional and neutral pictures, when event-related potentials and oscillatory activity were measured (Session 1). Crucially, after a 1-day interval, the same participants were exposed to a second habituation phase with the same stimuli that had been seen before. Results showed that the attenuation of the late positive potential (LPP) affective modulation prompted throughout repetitions of Session 1 remained unchanged after a 1-day interval, and this between-session habituation effect, which was specific to repeated exemplars, was consistent across different emotional contents. Alpha desynchronization was clearly enhanced for pictures of erotica and mutilation and this modulatory pattern remained fairly stable over repetitions. Altogether, these findings suggest that LPP affective habituation is not a short-living learning process, but, rather, reflects a strengthened long-term memory representation of specific repeated stimuli.

The effect of unusualness on the functional field of view in unsafe scenes

ABSTRACTTwo experiments were conducted to investigate the effect of unusualness of visually presented unsafe items on the functional field of view. In each experiment, after presenting a word indicating a certain context, we presented a picture including a safe or unsafe daily-life item. Participants were asked to identify a target digit that was briefly presented at the periphery immediately after the picture disappeared. Unusualness was manipulated by varying the incongruency between the item and the word, irrespective of the unsafety of the item. The affective habituation was controlled by using between-participants (Experiment 1) and within-block designs (Experiment 2) for the unsafety manipulation. Target identification accuracy was impaired by the incongruency when the items were unsafe, but this impairment was removed by the affective habituation. These results suggest that unusualness and unsafety have a role in the shrinkage of the functional field of view.

Opponent Effects of Hyperarousal and Re-experiencing on Affective Habituation in Posttraumatic Stress Disorder

BackgroundAberrant emotion processing is a hallmark of posttraumatic stress disorder (PTSD), with neurobiological models suggesting both heightened neural reactivity and diminished habituation to aversive stimuli. However, empirical work suggests that these response patterns may be specific to subsets of those with PTSD. This study investigates the unique contributions of PTSD symptom clusters (re-experiencing, avoidance and numbing, and hyperarousal) to neural reactivity and habituation to negative stimuli in combat-exposed veterans. MethodsNinety-five combat-exposed veterans (46 with PTSD) and 53 community volunteers underwent functional magnetic resonance imaging while viewing emotional images. This study examined the relationship between symptom cluster severity and hemodynamic responses to negative compared with neutral images (NEG>NEU). ResultsVeterans exhibited comparable mean and habituation-related responses for NEG>NEU, relative to civilians. However, among veterans, habituation, but not mean response, was differentially related to PTSD symptom severity. Hyperarousal symptoms were related to decreased habituation for NEG>NEU in a network of regions, including superior and inferior frontal gyri, ventromedial prefrontal cortex, superior and middle temporal gyri, and anterior insula. In contrast, re-experiencing symptoms were associated with increased habituation in a similar network. Furthermore, re-experiencing severity was positively related to amygdalar functional connectivity with the left inferior frontal gyrus and dorsal anterior cingulate cortex for NEG>NEU. ConclusionsThese results indicate that hyperarousal symptoms in combat-related PTSD are associated with decreased neural habituation to aversive stimuli. These impairments are partially mitigated in the presence of re-experiencing symptoms, such that during exposure to negative stimuli, re-experiencing symptoms are positively associated with amygdalar connectivity to prefrontal regions implicated in affective suppression.

Reduced Phrenic Motoneuron Recruitment during Sustained Inspiratory Threshold Loading Compared to Single-Breath Loading: A Twitch Interpolation Study

In humans, inspiratory constraints engage cortical networks involving the supplementary motor area. Functional magnetic resonance imaging (fMRI) shows that the spread and intensity of the corresponding respiratory-related cortical activation dramatically decrease when a discrete load becomes sustained. This has been interpreted as reflecting motor cortical reorganization and automatisation, but could proceed from sensory and/or affective habituation. To corroborate the existence of motor reorganization between single-breath and sustained inspiratory loading (namely changes in motor neurones recruitment), we conducted a diaphragm twitch interpolation study based on the hypothesis that motor reorganization should result in changes in the twitch interpolation slope. Fourteen healthy subjects (age: 21–40 years) were studied. Bilateral phrenic stimulation was delivered at rest, upon prepared and targeted voluntary inspiratory efforts (“vol”), upon unprepared inspiratory efforts against a single-breath inspiratory threshold load (“single-breath”), and upon sustained inspiratory efforts against the same type of load (“continuous”). The slope of the relationship between diaphragm twitch transdiaphragmatic pressure and the underlying transdiaphragmatic pressure was −1.1 ± 0.2 during “vol,” −1.5 ± 0.7 during “single-breath,” and −0.6 ± 0.4 during “continuous” (all slopes expressed in percent of baseline.percent of baseline−1) all comparisons significant at the 5% level. The contribution of the diaphragm to inspiration, as assessed by the gastric pressure to transdiaphragmatic pressure ratio, was 31 ± 17% during “vol,” 22 ± 16% during “single-breath” (p = 0.13), and 19 ± 9% during “continuous” (p = 0.0015 vs. “vol”). This study shows that the relationship between the amplitude of the transdiaphragmatic pressure produced by a diaphragm twitch and its counterpart produced by the underlying diaphragm contraction is not unequivocal. If twitch interpolation is interpreted as reflecting motoneuron recruitment, this study supports motor reorganization compatible with “diaphragm sparing” when an inspiratory threshold load becomes sustained.

Brand Suicide? Memory and Liking of Negative Brand Names.

Negative brand names are surprisingly common in the marketplace (e.g., Poison perfume; Hell pizza, and Monster energy drink), yet their effects on consumer behavior are currently unknown. Three studies investigated the effects of negative brand name valence on brand name memory and liking of a branded product. Study 1 demonstrates that relative to non-negative brand names, negative brand names and their associated logos are better recognised. Studies 2 and 3 demonstrate that negative valence of a brand name tends to have a detrimental influence on product evaluation with evaluations worsening as negative valence increases. However, evaluation is also dependent on brand name arousal, with high arousal brand names resulting in more positive evaluations, such that moderately negative brand names are equally as attractive as some non-negative brand names. Study 3 shows evidence for affective habituation, whereby the effects of negative valence reduce with repeated exposures to some classes of negative brand name.

Voter Habituation in Developing Democracy: Evidence from South Africa's First Democratic Election

In a developing democracy, can elections change the behavior of participating citizens? I identify the effect of participating in South Africa's first democratic election in 1994 on future electoral participation, and present the first well-identified evidence that past participation increases future participation in a developing democracy. Participating in 1994 has an intent-to-treat effect of 2.9 percentage points on future participation, and an average treatment effect of between 3.5 and 8.5 percentage points. Given low turnout rates, these effects account for 7-20% of the size of the electorate. To explain this result I introduce a novel theoretical explanation that draws on psychological research -- affective experience habituation. I argue that persistence (or habituation) in voting behavior is partly driven by the creation of associations between first time voting and positive emotional states. The theory is tested within the context of the 1994 election by exploiting racial and geographic variation in electoral experiences.

Repeated exposure to odors induces affective habituation of perception and sniffing.

Olfactory perception, and especially hedonic evaluation of odors, is highly flexible, but some mechanisms involved in this flexibility remain to be elucidated. In the present study we aimed at better understanding how repeated exposure to odors can affect their pleasantness. We tested the hypothesis of an affective habituation to the stimuli, namely a decrease of emotional intensity over repetitions. More specifically, we tested whether this effect is subject to inter-individual variability and whether it can also be observed at the olfactomotor level. Twenty-six participants took part in the experiment during which they had to smell two odorants, anise and chocolate, presented 20 times each. On each trial, sniff duration and volume were recorded and paired with ratings of odor pleasantness and intensity. For each smell, we distinguished between “likers” and “dislikers,” namely individuals giving positive and negative initial hedonic evaluations. Results showed a significant decrease in pleasantness with time when the odor was initially pleasant (“likers”), while unpleasantness remained stable or slightly decreased when the odor was initially unpleasant (“dislikers”). This deviation toward neutrality was interpreted as affective habituation. This effect was all the more robust as it was observed for both odors and corroborated by sniffing, an objective measurement of odor pleasantness. Affective habituation to odors can be interpreted as an adaptive response to stimuli that prove over time to be devoid of positive or negative outcome on the organism. This study contributes to a better understanding of how olfactory preferences are shaped through exposure, depending on the individual's own initial perception of the odor.

Attentional disengagement is modulated by the offset of unpleasant pictures: a saccadic reaction time study

We studied the influence of passively viewing a picture on saccade latencies to peripheral targets. Thirty-two volunteers were instructed to look at a central picture, wait for the onset of a peripheral target, and execute a saccade toward it as quickly as possible — saccadic reaction time (SRT). The central picture (neutral or unpleasant) could be turned off simultaneously with target onset (the no-gap condition) or 200ms prior to target onset (the gap-200 condition). We found that saccade latencies were influenced by emotional valence and condition. In the no-gap condition, SRTs were longer after viewing unpleasant pictures. In the gap-200 condition, the pattern was reversed, and unpleasant pictures induced shorter SRTs in relation to neutral pictures. Furthermore, the influence of unpleasant pictures gradually decreased when images were re-exposed to the participants — affective habituation. The results are discussed in terms of attentional avoidance and disengagement from unpleasant emotional pictures.

The subliminal affective habituation eliminates the Inhibition of return.

The subliminal affective habituation eliminates the Inhibition of return.

Deconstructing the hedonic treadmill: Is happiness autoregressive?

Affective habituation is well-documented in social sciences: people seem to adapt to many life events, ranging from lottery windfalls to terminal illnesses. A group of studies have tried to measure habituation by seeing how lagged values of life events affect present happiness. We propose an additional adaptation channel: current happiness may depend directly on past happiness, which amounts to assessing whether happiness is autoregressive. We run dynamic happiness regressions using individual-level panel data from the German Socio-Economic Panel Study, the Japanese Panel Survey of Consumers, the British Household Panel Survey and the Swiss Household Panel. As in previous studies, the coefficients on lagged events (e.g., becoming unemployed, getting married) suggest strong habituation. However, all the econometric models suggest that the coefficient on lagged happiness is positive and significant. We discuss whether this may be evidence of happiness having an inertial force (besides the usual habituation channel).

Retrocausal Habituation and Induction of Boredom: A Successful Replication of Bem (2010; Studies 5 and 7)

Bem (2010) reports evidence suggestive of unconscious retrocausal processes in human cognition. Bem’s findings appear to imply that under some circumstances, human subjects may display psychologically or physiologically meaningful reactions to future stimuli about whose occurrence they have no direct or indirect knowledge. This working paper describes a group replication attempt of Bem's (2010) studies 5 and 7, i.e. time-reversed affective habituation to highly arousing negative pictures and retrocausal induction of boredom/aversion to low arousing, mildly positive pictures (n=70). Evidence suggestive of a retrocausal influence of later stimulus display on subjects' preference ratings was found for affective habituation with high arousing negative stimuli; further, as in Bem's study 7, retrocausal boredom induction was found for subjects high in boredom proneness.

Time Scales of Auditory Habituation in the Amygdala and Cerebral Cortex

Habituation is a fundamental form of learning manifested by a decrement of neuronal responses to repeated sensory stimulation. In addition, habituation is also known to occur on the behavioral level, manifested by reduced emotional reactions to repeatedly presented affective stimuli. It is, however, not clear which brain areas show a decline in activity during repeated sensory stimulation on the same time scale as reduced valence and arousal experience and whether these areas can be delineated from other brain areas with habituation effects on faster or slower time scales. These questions were addressed using functional magnetic resonance imaging acquired during repeated stimulation with piano melodies. The magnitude of functional responses in the laterobasal amygdala and in related cortical areas and that of valence and arousal ratings, given after each music presentation, declined in parallel over the experiment. In contrast to this long-term habituation (43 min), short-term decreases occurring within seconds were found in the primary auditory cortex. Sustained responses that remained throughout the whole investigated time period were detected in the ventrolateral prefrontal cortex extending to the dorsal part of the anterior insular cortex. These findings identify an amygdalocortical network that forms the potential basis of affective habituation in humans.

Deconstructing the Hedonic Treadmill: Is Happiness Autoregressive?

Affective habituation is well-documented in social sciences: people seem to adapt to many life events, ranging from lottery windfalls to terminal illnesses. A group of studies have tried to measure habituation by seeing how lagged values of life events affect present happiness. We propose an additional adaptation channel: current happiness may depend directly on past happiness, which amounts to assessing whether happiness is autoregressive. We run dynamic happiness regressions using individual-level panel data from the four large household panels. As in previous studies, the coefficients on lagged events (e.g., becoming unemployed, getting married) suggest habituation. However, all the econometric models suggest that the coefficient on lagged happiness is positive and significant. We discuss whether this may be evidence of happiness having an inertial force (besides the usual habituation channel).

Investigating the dynamics of affect: Psychological mechanisms of affective habituation to pleasurable stimuli

Affective habituation (i.e., reductions in stimulus-evoked affective reactions as a result of previous exposure) may serve a functional purpose. However, little is know about the psychological mechanisms underlying this process. To elucidate the characteristics of affective habituation, two experiments that examined affective reactions to repeated exposures of pleasurable stimuli were conducted. Results of these experiments indicated that habituation trajectories are characterized by linear decreases in affect. Results also demonstrated that habituation can be slowed by the introduction of novel stimuli (i.e., “novelty effects”), effects that are dimensional (rather than taxonic) in nature. Experiment 2 demonstrated that habituation is mediated by conceptual rather than perceptual processes. Depressed and anhedonic individuals were not more susceptible to habituation in either experiment. The current findings and previous theorizing suggest that habituation may be an important component of an adaptive affective processing system that promotes effective responses to salient stimuli and prevents compulsive reward-seeking behavior.