The role of mood and arousal in the effect of background music on attentional state and performance during a sustained attention task.

Across two online experiments, this study explored the effect of preferred background music on attentional state and performance, as well as on mood and arousal, during a vigilance task. It extended recent laboratory findings-showing an increase in task-focus and decrease in mind-wandering states with music-to environments with more distractions around participants. Participants-people who normally listen to background music during attention-demanding tasks-completed the vigilance task in their homes both with and without their chosen music and reported their attentional state, subjective arousal, and mood valence throughout the task. Experiment 1 compared music to relative silence and Experiment 2 compared music against the backdrop of continuous noise to continuous noise alone. In both experiments, music decreased mind-wandering and increased task-focus. Unlike in previous laboratory studies, in both experiments music also led to faster reaction times while increasing low-arousal external-distraction states. Importantly, mood and arousal increased with music and were shown to mediate its effects on reaction time and for the first time attentional state, both separately and together. Serial mediation effects were mostly confined to models where mood was entered first and arousal second and were consistent with the mood-arousal account of the impact of background music listening.

'Staying Hot': Investigating the influence of overnight conditions on the penile skin temperature during male sexual arousal-A novel methodology for nocturnal erection detection.

Objective: The objective of this study is to assess the impact of overnight environmental conditions on erectile penile temperature within a controlled setting, with the aim of investigating the feasibility of using temperature measurements for nocturnal erection detection in erectile dysfunction diagnostics. Subjects/patients and methods: We conducted a proof-of-concept study involving 10 healthy male participants aged 20 to 25. The study was carried out at the Department of Urology, St. Antonius Ziekenhuis, the Netherlands. Penile temperature thermistor measurements were taken during visually aroused erections of participants in naked state and in simulated overnight condition (underwear and blankets). Main outcome variables were peak and baseline temperature during erectile periods. To minimize the impact of differences in erectile strength and duration between consecutive measurements, we applied randomization to the order of the environmental conditions. Results: We observed a significant increase in penile temperature during erection in both the naked (p < 0.01) and simulated overnight condition (p < 0.01). The mean temperature increase was 1.70 and 0.67°C, respectively. While penile temperature returned to baseline immediately after naked erections, the 'Staying Hot effect' was noted in the simulated overnight condition measurements, where the temperature remained elevated at peak temperature for the entire 30-min period following the erection. Conclusions: The findings from this study indicate that the penile temperature not only significantly increases during naked sexual arousal but is also detectable under simulated overnight conditions. This underscores the potential of using temperature measurements for nocturnal erection detection, representing a crucial initial step in developing a modernized, non-invasive sensor system for ambulatory erectile dysfunction diagnostics. Further research, including an overnight study, is needed to gain insights into the feasibility of utilizing penile temperature measurements for nocturnal erection detection and to assess the impact of the 'Staying Hot effect' on subsequent erection detection.

How music-induced emotions affect sexual attraction: evolutionary implications.

More than a century ago, Darwin proposed a putative role for music in sexual attraction (i.e., sex appeal), a hypothesis that has recently gained traction in the field of music psychology. In his writings, Darwin particularly emphasized the charming aspects of music. Across a broad range of cultures, music has a profound impact on humans' feelings, thoughts and behavior. Human mate choice is determined by the interplay of several factors. A number of studies have shown that music and musicality (i.e., the ability to produce and enjoy music) exert a positive influence on the evaluation of potential sexual partners. Here, we critically review the latest empirical literature on how and why music and musicality affect sexual attraction by considering the role of music-induced emotion and arousal in listeners as well as other socio-biological mechanisms. Following a short overview of current theories about the origins of musicality, we present studies that examine the impact of music and musicality on sexual attraction in different social settings. We differentiate between emotion-based influences related to the subjective experience of music as sound and effects associated with perceived musical ability or creativity in a potential partner. By integrating studies using various behavioral methods, we link current research strands that investigate how music influences sexual attraction and suggest promising avenues for future research.

Electroencephalography as an objective method for assessing subjective emotions during the application of cream.

OBJECTIVE: To compare emotional responses elicited by four cosmetic products on different sensory modalities (smell, visual, and touch), and analyze the link between objective instrumental analysis results and subjective evaluation of participants occurring within dimensional valence-arousal model of emotions. METHODS: In this study, four cream products exhibiting variations in olfactory perception, visual appearance and perception usability were selected. Electroencephalography (EEG) and a subjective emotion scale were used to assess participants' emotional responses during the sensory experience of utilizing the creams. RESULTS: The study revealed that the objective emotional valence and arousal of different cream products exhibited certain variations at distinct stages of usage. The trend of valence differences induced by different products measured by EEG at the same stage was almost as same as measured by subjective evaluation. The correspondence between the valence measured by EEG closely approximated that obtained through subjective evaluation across various products at distinct stages of usage. These findings demonstrate a significant correlation between EEG-based valence and subjective valence, however, no such relationship was observed for arousal. CONCLUSION: This study demonstrates the feasibility of using EEG as a method to assess emotions elicited by various stages of cosmetics application, including smelling, looking, rubbing, and afterfeel. This technique serves as a valuable supplement to traditional methods for examining emotional responses by providing more objective evidence.

The Affective Responses to Moderate Physical Activity: A Further Study to Prove the Convergent and the Discriminant Validity for the German Versions of the Feeling Scale and the Felt Arousal Scale.

The present study proves the construct validity of the German versions of the Feeling Scale (FS) and the Felt Arousal Scale (FAS) for measuring the affective responses (affective valence and arousal) for a moderate-intensity jogging (JG) exercise. In previous studies, both scales were validated for a high-intensity bicycle ergometer exercise and for relaxation techniques. In the present study, 194 participants performed the JG exercise for 45 min and completed the FS and the FAS, as well as the Self-Assessment Manikin (SAM), for a self-other comparison in a pre-test-intervention-post-test design. The results of the correlation analyses replicated the previous findings for the high-intensity bicycle ergometer exercise and the relaxation techniques, revealing significant positive correlations for the valence dimension between the FS and the SAM-Pleasure subscale (r = 0.50) and for the arousal dimension between the FAS and the SAM-Arousal subscale (r = 0.16). These findings suggest that the German versions of the FS and the FAS are also suitable for exercises of moderate intensity.

Impact of mindfulness versus supportive sex education on stress in women with sexual interest/arousal disorder.

Low desire in women is the most common sexual difficulty, and stress has been identified as a significant predictor of symptoms. We evaluated a mindfulness-based cognitive therapy (MBCT) group treatment versus a sex education comparison group treatment (STEP) on self-reported stress and on the physiological stress response measured via morning-to-evening cortisol slope in 148 women with a diagnosis of sexual interest/arousal disorder (SIAD). Perceived stress decreased following treatment in both groups, and significantly more after MBCT. The cortisol slope was steeper (indicative of better stress system regulation) from pre-treatment to 6-month follow-up, with no differences between the groups. As an exploratory analysis, we found that the reduction in perceived stress predicted increases in sexual desire and decreases in sex-related distress for participants after MBCT only. These findings suggest that group mindfulness targeting women with low sexual desire leads to improvements in self-reported and physiological stress, with improvements in self-reported stress partially accounting for improvements in sexual desire and distress.

Effect of daridorexant on sleep architecture in patients with chronic insomnia disorder - A pooled post hoc analysis of two randomized Phase 3 clinical studies.

STUDY OBJECTIVES: Post-hoc analysis to evaluate the effect of daridorexant on sleep architecture in people with insomnia, focusing on features associated with hyperarousal. METHODS: We studied sleep architecture in adults with chronic insomnia disorder from two randomized Phase 3 clinical studies (Clinicaltrials.gov: NCT03545191 and NCT03575104) investigating 3 months of daridorexant treatment (placebo, daridorexant 25 mg, daridorexant 50 mg). We analyzed sleep-wake transition probabilities, EEG spectra and sleep spindle properties including density, dispersion, and slow oscillation phase coupling. The Wake EEG Similarity Index (WESI) was determined using a machine learning algorithm analyzing the spectral profile of the EEG. RESULTS: At Month 3, daridorexant 50 mg decreased Wake-to-Wake transition probabilities (P<0.05) and increased the probability of transitions from Wake-to-N1 (P<0.05), N2 (P<0.05), and REM sleep (P<0.05), as well as from N1-to-N2 (P<0.05) compared to baseline and placebo. Daridorexant 50 mg decreased relative beta power during Wake (P=0.011) and N1 (P<0.001) compared to baseline and placebo. During Wake, relative alpha power decreased (P<0.001) and relative delta power increased (P<0.001) compared to placebo. Daridorexant did not alter EEG spectra bands in N2, N3, and REM stages or in sleep spindle activity. Daridorexant decreased the WESI score during Wake compared to baseline (P=0.004). Effects with 50 mg were consistent between Month 1 and Month 3 and less pronounced with 25 mg. CONCLUSION: Daridorexant reduced EEG features associated with hyperarousal as indicated by reduced Wake-to-Wake transition probabilities and enhanced spectral features associated with drowsiness and sleep during Wake and N1.

Anesthesia and the neurobiology of consciousness.

In the 19th century, the discovery of general anesthesia revolutionized medical care. In the 21st century, anesthetics have become indispensable tools to study consciousness. Here, I review key aspects of the relationship between anesthesia and the neurobiology of consciousness, including interfaces of sleep and anesthetic mechanisms, anesthesia and primary sensory processing, the effects of anesthetics on large-scale functional brain networks, and mechanisms of arousal from anesthesia. I discuss the implications of the data derived from the anesthetized state for the science of consciousness and then conclude with outstanding questions, reflections, and future directions.

Detection of arousal and valence from facial expressions and physiological responses evoked by different types of stressors.

Automatically detecting mental state such as stress from video images of the face could support evaluating stress responses in applicants for high risk jobs or contribute to timely stress detection in challenging operational settings (e.g., aircrew, command center operators). Challenges in automatically estimating mental state include the generalization of models across contexts and across participants. We here aim to create robust models by training them using data from different contexts and including physiological features. Fifty-one participants were exposed to different types of stressors (cognitive, social evaluative and startle) and baseline variants of the stressors. Video, electrocardiogram (ECG), electrodermal activity (EDA) and self-reports (arousal and valence) were recorded. Logistic regression models aimed to classify between high and low arousal and valence across participants, where "high" and "low" were defined relative to the center of the rating scale. Accuracy scores of different models were evaluated: models trained and tested within a specific context (either a baseline or stressor variant of a task), intermediate context (baseline and stressor variant of a task), or general context (all conditions together). Furthermore, for these different model variants, only the video data was included, only the physiological data, or both video and physiological data. We found that all (video, physiological and video-physio) models could successfully distinguish between high- and low-rated arousal and valence, though performance tended to be better for (1) arousal than valence, (2) specific context than intermediate and general contexts, (3) video-physio data than video or physiological data alone. Automatic feature selection resulted in inclusion of 3-20 features, where the models based on video-physio data usually included features from video, ECG and EDA. Still, performance of video-only models approached the performance of video-physio models. Arousal and valence ratings by three experienced human observers scores based on part of the video data did not match with self-reports. In sum, we showed that it is possible to automatically monitor arousal and valence even in relatively general contexts and better than humans can (in the given circumstances), and that non-contact video images of faces capture an important part of the information, which has practical advantages.

Arousal and performance: revisiting the famous inverted-U-shaped curve.

Arousal level is thought to be a key determinant of variability in cognitive performance. In a recent study, Beerendonk, Mejías et al. show that peak performance in decision-making tasks is reached at moderate levels of arousal. They also propose a neurobiologically informed computational model that can explain the inverted-U-shaped relationship.

The effect of sleep position on sleep bruxism in adults with obstructive sleep apnea.

BACKGROUND: Most of the respiratory events in adults with obstructive sleep apnea (OSA) occurs in supine position. It has been reported that the contraction of masseter muscles is dependent on the occurrence of arousals rather than on the occurrence of respiratory events. OBJECTIVES: This study had two aims: (1) to compare the rhythmic masticatory muscle activity (RMMA) index in supine position (RMMA_sup) and in non-supine positions (RMMA_nsup) in adults with OSA; and (2) to determine the associations between RMMA index in both supine position and non-supine positions on the one hand, and several demographic and polysomnographic variables on the other hand. METHODS: One hundred OSA participants (36 females and 64 males; mean age = 50.3 years (SD = 10.5)) were selected randomly from among patients with a full-night polysomnographic recording. RMMA_sup index and RMMA_nsup index were compared using Mann-Whitney U-test. Multivariate linear regression analyses were used to predict RMMA index both in supine and non-supine positions based on several demographic and polysomnographic variables. RESULTS: In patients with OSA, the RMMA_sup index was significantly higher than the RMMA_nsup index (p < .001). RMMA_sup index was significantly associated with the arousal index (p = .002) and arousal index in supine position (p < .001). RMMA_nsup index was only significantly associated with the arousal index in non-supine positions (p = .004). CONCLUSION: Within the limitations of this study, RMMAs occur more frequently in supine position than in non-supine positions in patients with OSA. In both sleep positions, RMMAs are associated with arousals.

Genital arousal and responsive desire among women with and without sexual interest/arousal disorder symptoms.

BACKGROUND: Models depicting sexual desire as responsive to sexual arousal may be particularly apt for women experiencing arousal or desire difficulties, and the degree to which arousal triggers desire may depend on the relationship context and desire target and timing-yet, these associations have not been directly tested among women with and without sexual interest/arousal disorder (SIAD). AIM: To assess the role of SIAD status and relationship satisfaction in the associations between genital arousal and 4 types of responsive desire. METHODS: One hundred women (n = 27 meeting diagnostic criteria for SIAD) in romantic relationships with men viewed a sexual film (pleasurable intimate depiction of oral sex and penile-vaginal intercourse) while their genital arousal was recorded via vaginal photoplethysmography (n = 63) or thermal imaging of the labia (n = 37). Partner and solitary desire was assessed immediately before and after the film (immediate desire) and 3 days later (delayed desire). OUTCOMES: Outcomes consisted of genital response (z scored by method) and associations between genital response and responsive sexual desire. RESULTS: The key difference between women with and without SIAD was not in their ability to experience genital arousal but in how their genital responses translated to responsive sexual desire. Women with SIAD actually exhibited greater genital arousal than unaffected women. Associations between genital arousal and desire were significant only for women with SIAD and depended on relationship satisfaction and desire type. For women with SIAD with low relationship satisfaction, higher arousal predicted lower immediate desire for a partner; for those with high relationship satisfaction, arousal was either positively related (vaginal photoplethysmography) or unrelated (thermal imaging of the labia) to immediate desire for a partner. Associations with other desire types were not significant. CLINICAL IMPLICATIONS: Patterns of genital arousal and partner-specific responsive desire among women affected with SIAD were indicative of an avoidance model in response to heightened genital arousal, unless relationship satisfaction was high; attending to genital arousal sensations could be a means of triggering sexual desire for women with SIAD who are satisfied in their relationships. STRENGTHS AND LIMITATIONS: This is one of the first sexual psychophysiologic studies to connect relationship factors to patterns of sexual response. The differing arousal assessment procedures and lack of official diagnosis may have attenuated results. The homogeneous sample and in-person session requirement limit generalizability. CONCLUSION: When compared with unaffected women, women affected by SIAD may exhibit stronger arousal responses with sufficiently incentivized sexual stimuli, and the connection between their genital arousal and responsive desire for their partners may be stronger and more dependent on relationship context.

Dynamic skin behaviors in cephalopods.

The coleoid cephalopods (cuttlefish, octopus, and squid) are a group of soft-bodied mollusks that exhibit a wealth of complex behaviors, including dynamic camouflage, object mimicry, skin-based visual communication, and dynamic body patterns during sleep. Many of these behaviors are visually driven and engage the animals' color changing skin, a pixelated display that is directly controlled by neurons projecting from the brain. Thus, cephalopod skin provides a direct readout of neural activity in the brain. During camouflage, cephalopods recreate on their skin an approximation of what they see, providing a window into perceptual processes in the brain. Additionally, cephalopods communicate their internal state during social encounters using innate skin patterns, and create waves of pigmentation on their skin during periods of arousal. Thus, by leveraging the visual displays of cephalopods, we can gain insight into how the external world is represented in the brain and how this representation is transformed into a recapitulation of the world on the skin. Here, we describe the rich skin behaviors of the coleoid cephalopods, what is known about cephalopod neuroanatomy, and how advancements in gene editing, machine learning, optical imaging, and electrophysiological tools may provide an opportunity to explore the neural bases of these fascinating behaviors.

The Exercise Intensity-Music-Tempo Preference Relationship: A Decennial Revisit.

Tempo is a key determinant of the motivational effects of music during exercise and has been the focus of numerous empirical studies (e.g., Karageorghis & Jones, 2014). The present study sought to address the limitations of previous related work and revisit the relationship between exercise intensity and music-tempo preference using unfamiliar, non-lyrical music (to isolate the tempo manipulation). A within-within experimental design was employed to test hypotheses pertaining to the non-linear relationship and associated psychological outcomes (e.g., core affect and state attention). Twenty-four participants (Mage = 20.6 years, SD = .92 years) exercised at five intensities (10% of peak VO2 below ventilatory threshold [VT]; 5% of peak VO2 below VT, at VT, midway between VT and the respiratory compensation point [RCP], and at RCP) during which they were administered music tracks at four tempi (90 bpm, 110 bpm, 130 bpm and 150 bpm) and a no-music control. A music liking item, measures of core affect (valence and arousal), attentional focus and perceived exertion were recorded during the exercise bouts. Results indicated that unlike previous findings with familiar, lyrical music, there was no discernible relationship between exercise intensity and preference for music tempo. The most positive psychological outcomes were associated with fast-tempo music. In accord with previous findings, slow-tempo music attracted low liking scores and the least desirable psychological outcomes at every exercise intensity. The present findings have implications for the use of unfamiliar, non-lyrical music during exercise. Specifically, that such music should be ∼10 bpm faster than familiar, lyrical music.

Influence of visual feedback and cognitive challenge on the age-related changes in force steadiness.

Force steadiness can be influenced by visual feedback as well as presence of a cognitive tasks and potentially differs with age and sex. This study determined the impact of altered visual feedback on force steadiness in the presence of a difficult cognitive challenge in young and older men and women. Forty-nine young (19-30 yr; 25 women, 24 men) and 25 older (60-85 yr; 15 women; 10 men) performed low force (5% of maximum) static contractions with the elbow flexor muscles in the presence and absence of a cognitive challenge (counting backwards by 13) either with low or high visual feedback gain. The cognitive challenge reduced force steadiness (increased force fluctuation amplitude) particularly in women (cognitive challenge × sex: P < 0.05) and older individuals (cognitive challenge × age: P < 0.05). Force steadiness improved with high-gain visual feedback compared with low-gain visual feedback (P < 0.01) for all groups (all interactions: P > 0.05). Manipulation of visual feedback had no influence on the reduced force steadiness in presence of the cognitive challenge for all groups (all P > 0.05). These findings indicate that older individuals and women have greater risk of impaired motor performance of the upper extremity if steadiness is required during a low-force static contraction. Manipulation of visual feedback had minimal effects on the reduced force steadiness in presence of a difficult cognitive challenge.

Memory enhancement for emotional words is attributed to both valence and arousal.

We do not memorize items in our surroundings with equal priority. Previous literature has widely shown that emotional stimuli are better remembered than neutral stimuli. However, given emotional stimuli and neutral stimuli often differ in both valence and arousal dimensions, it remains unclear whether the enhancement effects can be attributed to valence, or just to arousal. Importantly, most prior studies relied on a relatively small number of stimuli and non-emotional factors such as word length, imageability and other confounds were hard to control. To address these challenges, we analyzed multiple large databases of recognition memory and free recall tasks from previous research by items with many lexical and semantic covariates included, examining the effects of valence or arousal when controlling for each other. Our results showed a U-shaped relationship between valence and memory performance for both recognition and free recall, and a linear relationship between arousal and memory performance for both tasks. These findings showed that the memory enhancement effects can be attributed to both valence and arousal. We demonstrated these effects with generalizability across many stimuli and controlled for non-emotional factors. Together, these findings disentangle the contribution of valence and arousal in emotional memory enhancement effects and provide insights for current major theories of emotional memory.

Attention Mobilization as a Modulator of Listening Effort: Evidence From Pupillometry.

Listening to speech in noise can require substantial mental effort, even among younger normal-hearing adults. The task-evoked pupil response (TEPR) has been shown to track the increased effort exerted to recognize words or sentences in increasing noise. However, few studies have examined the trajectory of listening effort across longer, more natural, stretches of speech, or the extent to which expectations about upcoming listening difficulty modulate the TEPR. Seventeen younger normal-hearing adults listened to 60-s-long audiobook passages, repeated three times in a row, at two different signal-to-noise ratios (SNRs) while pupil size was recorded. There was a significant interaction between SNR, repetition, and baseline pupil size on sustained listening effort. At lower baseline pupil sizes, potentially reflecting lower attention mobilization, TEPRs were more sustained in the harder SNR condition, particularly when attention mobilization remained low by the third presentation. At intermediate baseline pupil sizes, differences between conditions were largely absent, suggesting these listeners had optimally mobilized their attention for both SNRs. Lastly, at higher baseline pupil sizes, potentially reflecting overmobilization of attention, the effect of SNR was initially reversed for the second and third presentations: participants initially appeared to disengage in the harder SNR condition, resulting in reduced TEPRs that recovered in the second half of the story. Together, these findings suggest that the unfolding of listening effort over time depends critically on the extent to which individuals have successfully mobilized their attention in anticipation of difficult listening conditions.

Functionality of arousal-regulating brain circuitry at rest predicts human cognitive abilities.

Arousal state is regulated by subcortical neuromodulatory nuclei, such as locus coeruleus, which send wide-reaching projections to cortex. Whether higher-order cortical regions have the capacity to recruit neuromodulatory systems to aid cognition is unclear. Here, we hypothesized that select cortical regions activate the arousal system, which in turn modulates large-scale brain activity, creating a functional circuit predicting cognitive ability. We utilized the Human Connectome Project 7T functional magnetic resonance imaging dataset (N=149), acquired at rest with simultaneous eye tracking, along with extensive cognitive assessment for each subject. First, we discovered select frontoparietal cortical regions that drive large-scale spontaneous brain activity specifically via engaging the arousal system. Second, we show that the functionality of the arousal circuit driven by bilateral posterior cingulate cortex (associated with the default mode network) predicts subjects' cognitive abilities. This suggests that a cortical region that is typically associated with self-referential processing supports cognition by regulating the arousal system.

There is no happiness in positive affect: the pervasive misunderstanding of the rotated circumplex model.

Research on positive affect (PA) and negative affect (NA) is often guided by the rotational variant of the circumplex model of affect (RCMA). According to the RCMA, PA and NA are posited to be orthogonal, with PA ranging from the union of positive valence and high activation (e.g., excited) to the union of negative valence and low activation (e.g., sluggish), and NA ranging from the union of negative valence and high activation (e.g., distressed) to the union of positive valence and low activation (e.g., relaxed). However, many authors incorrectly interpret the RCMA as positing that positively valenced affect (i.e., pleasure) and negatively valenced affect (i.e., displeasure)-rather than PA and NA, as defined in the RCMA-are orthogonal. This "received view" of the RCMA has led to significant confusion in the literature. The present paper articulates the "received view" of the RCMA and characterizes its prevalence in psychological research. A random sample of 140 empirical research articles on affect published in 14 high-impact journals covering a range of psychological subdisciplines were reviewed. Over half of the articles subscribing to the RCMA showed evidence of the "received view," demonstrating that misuse of the terms PA and NA in the context of the RCMA is rampant in the psychological literature. To reduce continued confusion in the literature, we recommend abandoning use of the terms positive affect and negative affect. We further recommend referring to the two dimensions of the RCMA as positive activation and negative activation, and the two poles of the valence dimension as positive valence and negative valence (or pleasure and displeasure).

The role of arousal in the estimation of time-to-collision of threatening stimuli.

The accurate estimation of time-to-collision (TTC) is essential for the survival of organisms. Previous studies have revealed that the emotional properties of approaching stimuli can influence the estimation of TTC, indicating that approaching threatening stimuli are perceived to collide with the observers earlier than they actually do, and earlier than non-threatening stimuli. However, not only are threatening stimuli more negative in valence, but they also have higher arousal compared to non-threatening stimuli. Up to now, the effect of arousal on TTC estimation remains unclear. In addition, inconsistent findings may result from the different experimental settings employed in previous studies. To investigate whether the underestimation of TTC is attributed to threat or high arousal, three experiments with the same settings were conducted. In Experiment 1, the underestimation of TTC estimation of threatening stimuli was replicated when arousal was not controlled, in comparison to non-threatening stimuli. In Experiments 2 and 3, the underestimation effect of threatening stimuli disappeared when compared to positive stimuli with similar arousal. These findings suggest that being threatening alone is not sufficient to explain the underestimation effect, and arousal also plays a significant role in the TTC estimation of approaching stimuli. Further studies are required to validate the effect of arousal on TTC estimation, as no difference was observed in Experiment 3 between the estimated TTC of high and low arousal stimuli.