The role of physiological arousal in time perception: psychophysiological evidence from an emotion regulation paradigm

Time perception, crucial for adaptive behavior, has been shown to be altered by emotion. An arousal-dependent mechanism is proposed to account for such an effect. Yet, physiological measure of arousal related with emotional timing is still lacking. We addressed this question using skin conductance response (SCR) in an emotion regulation paradigm. Nineteen participants estimated durations of neutral and negative sounds by comparing them to a previously memorized duration. Instructions were given to attend either to temporal or to emotional stimulus features. Attending to emotion with negative sounds generated longer subjective duration and greater physiological arousal than attending to time. However, a shared-attention condition showed discrepancy between behavioral and physiological results. Supporting the idea of a link between autonomic arousal and subjective duration, our results however suggest that this relation is not as direct as was expected. Results are discussed within recent model linking time perception, emotion and awareness.     

Emotional time distortions: The fundamental role of arousal

An emotion-based lengthening effect on the perception of durations of emotional pictures has been assumed to result from an arousal-based mechanism, involving the activation of an internal clock system. The aim of this study was to systematically examine the arousal effect on time perception when different discrete emotions were considered. The participants were asked to verbally estimate the duration of emotional pictures from the International Affective Picture System (IAPS). The pictures varied either in arousal level, i.e., high/low-arousal, for the same discrete emotion (disgust or sadness) or in the depicted emotion, e.g., disgust/fear for pictures matched for arousal (high-arousal). The results systematically revealed a lengthening effect on the perception of the duration of the emotional compared to the neutral pictures and indicated that the magnitude of this effect increased with arousal level. Nevertheless, variations in time perception were observed for one and the same arousal level, with the duration of disgust-inducing pictures (e.g., body mutilation) being judged longer than that of fear-inducing pictures (e.g., snake). These results suggest that arousal is a fundamental mechanism mediating the effect of emotion on time perception. However, the effect cannot be reduced to arousal, since the impact of the content of pictures also plays a critical role.     

Changing the focus of attention: The interacting effect of valence and arousal

We examined how valence and arousal of an image influence visual attention. “Spotlight of attention” theory suggests that positive affect broadens, and negative affect narrows, one's aperture of attention, whereas the arousal theory literature suggests that arousal level is what modulates attentional focus, with highly arousing affect capturing attention, regardless of valence. In two experiments, a digit parity task was used to index the influence of valence, and arousal, on visual attention. Positive or negative images were displayed centrally on each trial, with single digits presented more peripherally (Experiment 1) or more centrally (Experiment 2) to the image. In both Experiments participants were slower, and less accurate at making parity decisions (e.g., both digits odd or both even) when the image was negative relative to positive, and of high arousal. For low arousal images, positive, relative to negative, valence images led to greater impairment of the digit parity task. Findings suggest that arousal level of images modulates the influence of valence on distribution of visual attention. Highly negative emotional images may command or capture attention, but there are other factors that can lead to attention capture, even in low arousing positive stimuli.     

Emotion and memory: A recognition advantage for positive and negative words independent of arousal

Much evidence indicates that emotion enhances memory, but the precise effects of the two primary factors of arousal and valence remain at issue. Moreover, the current knowledge of emotional memory enhancement is based mostly on small samples of extremely emotive stimuli presented in unnaturally high proportions without adequate affective, lexical, and semantic controls. To investigate how emotion affects memory under conditions of natural variation, we tested whether arousal and valence predicted recognition memory for over 2500 words that were not sampled for their emotionality, and we controlled a large variety of lexical and semantic factors. Both negative and positive stimuli were remembered better than neutral stimuli, whether arousing or calming. Arousal failed to predict recognition memory, either independently or interactively with valence. Results support models that posit a facilitative role of valence in memory. This study also highlights the importance of stimulus controls and experimental designs in research on emotional memory.     

The effect of pain and the anticipation of pain on temporal perception: A role for attention and arousal

The overestimation of the duration of fear-inducing stimuli relative to neutral stimuli is a robust finding within the temporal perception literature. Whilst this effect is consistently reported with auditory and visual stimuli, there has been little examination of whether it can be replicated using painful stimulation. The aim of the current study was, therefore, to explore how pain and the anticipation of pain affected perceived duration of time. A modified verbal estimation paradigm was developed in which participants estimated the duration of shapes previously conditioned to be associated with pain, compared to those not associated with pain. Duration estimates were significantly longer on trials in which pain was received or anticipated than on control trials. Slope and intercept analysis revealed that the anticipation of pain resulted in steeper slopes and greater intercept values than for control trials. The results suggest that increased arousal and attention, when anticipating and experiencing pain, result in longer perceived durations. The results are discussed in relation to internal clock theory and neurocognitive models of time perception.     

Using facial emotional stimuli in visual search experiments: The arousal factor explains contradictory results

For more than two decades, visual search experiments using pictures of emotional faces as stimuli have generated contradictory results. Evidence of a superior detection of angry faces compared to happy faces have been mixed with an equal amount of evidence in the opposite direction. In this article, we review this literature, and examine the hypothesis that the neglected stimulus factor of emotional arousal may explain these contradictory results. Through an extensive reanalysis of results from our own laboratory as well as from other researchers, we show that the arousal factor systematically influences the outcome of the reviewed visual search experiments, and may thus provide a key to the historical contradictions within this research field.     

Alteration of expected hemispheric asymmetries: valence and arousal effects in neuropsychological models of emotion

The relative advantage of the left (LH) over the right hemisphere (RH) in processing of verbal material for most individuals is well established. Nevertheless, several studies have reported the ability of positively and negatively valenced stimuli to enhance and reverse, respectively, the usual LH>RH asymmetry. These studies, however, have used baseline stimuli that differed from emotional stimuli on two dimensions (i.e., valence and verbal/nonverbal nature), creating interpretive difficulties as to whether differences across these conditions are due to differences in valence or the verbal/nonverbal nature of the primes used in the baseline condition. In addition, these studies, along with many others in the literature, have failed to control for potential confounding effects of arousal. Emotional stimuli vary on dimensions of valence as well as arousal and arousal may be asymmetrically presented in the brain therefore contributing to observed asymmetries. Taken together, these considerations underscore the importance of controlling for both valence as well as arousal in any investigation of the effects of emotional stimuli. The objectives of the present study were twofold: (1) to employ an appropriate baseline condition to render emotional stimuli vs. baseline stimuli comparisons meaningful and (2) to examine the extent to which emotional verbal stimuli, equated for arousal level, alter the expected LH>RH asymmetry in a consonant trigram task. Results demonstrated that when LH lateralized consonant trigram presentations were preceded by a positive prime, an enhancement of the expected LH>RH asymmetry was observed. In contrast, when trigram presentations lateralized to the RH were preceded by a negative prime, a complete reversal of the typical asymmetry was found with RH>LH performance. These results are analogous to the pattern of relative hemispheric activations observed for various mood states. Controlling for arousal in studies investigating asymmetries associated with emotional processing may allow more clear interpretation of data intended to test predictions of neuropsychological models of emotion. Moreover, equating stimuli on the dimension of arousal as well as valence may shed more light on conflicting findings with regard to perception vs. expression of emotion.     

Developmental reversals in false memory: Effects of emotional valence and arousal

Do the emotional valence and arousal of events distort children’s memories? Do valence and arousal modulate counterintuitive age increases in false memory? We investigated those questions in children, adolescents, and adults using the Cornell/Cortland Emotion Lists, a word list pool that induces false memories and in which valence and arousal can be manipulated factorially. False memories increased with age for unpresented semantic associates of word lists, and net accuracy (the ratio of true memory to total memory) decreased with age. These surprising developmental trends were more pronounced for negatively valenced materials than for positively valenced materials, they were more pronounced for high-arousal materials than for low-arousal materials, and developmental increases in the effects of arousal were small in comparison with developmental increases in the effects of valence. These findings have ramifications for legal applications of false memory research; materials that share the emotional hallmark of crimes (events that are negatively valenced and arousing) produced the largest age increases in false memory and the largest age declines in net accuracy.     

Stay calm! Regulating emotional responses by implementation intentions: Assessing the impact on physiological and subjective arousal

Implementation intention (IMP) has recently been highlighted as an effective emotion regulatory strategy. Most studies examining the effectiveness of IMPs to regulate emotion have relied on self-report measures of emotional change. In two studies we employed electrodermal activity (EDA) and heart rate (HR) in addition to arousal ratings (AR) to assess the impact of an IMP on emotional responses. In Study 1, 60 participants viewed neutral and two types of negative pictures (weapon vs. non-weapon) under the IMP “If I see a weapon, then I will stay calm and relaxed!” or no self-regulatory instructions (Control). In Study 2, additionally to the Control and IMP conditions, participants completed the picture rating task either under goal intention (GI) to stay calm and relaxed or warning instructions highlighting that some pictures contain weapons. In both studies, participants showed lower EDA, reduced HR deceleration and lower AR to the weapon pictures compared to the non-weapon pictures. In Study 2, the IMP was associated with lower EDA compared to the GI condition for the weapon pictures, but not compared to the weapon pictures in the Warning condition. ARs were lower for IMP compared to GI and Warning conditions for the weapon pictures.     

Avoid violence,rioting, and outrage; approach celebration,delight, and strength: Using large text corpora to compute valence,arousal, and the basic emotions

Ever since Aristotle discussed the issue in Book II of his Rhetoric, humans have attempted to identify a set of “basic emotion labels”. In this paper we propose an algorithmic method for evaluating sets of basic emotion labels that relies upon computed co-occurrence distances between words in a 12.7-billion-word corpus of unselected text from USENET discussion groups. Our method uses the relationship between human arousal and valence ratings collected for a large list of words, and the co-occurrence similarity between each word and emotion labels. We assess how well the words in each of 12 emotion label sets—proposed by various researchers over the past 118 years—predict the arousal and valence ratings on a test and validation dataset, each consisting of over 5970 items. We also assess how well these emotion labels predict lexical decision residuals (LDRTs), after co-varying out the effects attributable to basic lexical predictors. We then demonstrate a generalization of our method to determine the most predictive “basic” emotion labels from among all of the putative models of basic emotion that we considered. As well as contributing empirical data towards the development of a more rigorous definition of basic emotions, our method makes it possible to derive principled computational estimates of emotionality—specifically, of arousal and valence—for all words in the language.     

Emotion regulation in unipolar depression: the effects of acceptance and suppression of subjective emotional experience on the intensity and duration of sadness and negative affect

This study examined the effects of emotional suppression and acceptance in a depressed sample. Sixty participants with diagnoses of unipolar depression completed a questionnaire packet and participated in an experiment. The experiment utilized two conditions to explore correlates of the spontaneous use of emotion regulation strategies and the effects of an experimental manipulation of acceptance and suppression. Results demonstrated that suppression produced short-term reductions in sadness. Notably, anxiety about the experience of depressed mood influenced the efficacy of emotional suppression with findings showing that suppression was no longer effective at moderate and higher levels of anxiety about the experience of depressed mood. Implications of study findings for understanding emotion dysregulation in depressive disorders and the treatment of depression are discussed.     

TMS effects on subjective and objective measures of vision: stimulation intensity and pre- versus post-stimulus masking

Transcranial magnetic stimulation (TMS) can be used to mask visual stimuli, disrupting visual task performance or preventing visual awareness. While TMS masking studies generally fix stimulation intensity, we hypothesized that varying the intensity of TMS pulses in a masking paradigm might inform several ongoing debates concerning TMS disruption of vision as measured subjectively versus objectively, and pre-stimulus (forward) versus post-stimulus (backward) TMS masking. We here show that both pre-stimulus TMS pulses and post-stimulus TMS pulses could strongly mask visual stimuli. We found no dissociations between TMS effects on the subjective and objective measures of vision for any masking window or intensity, ruling out the option that TMS intensity levels determine whether dissociations between subjective and objective vision are obtained. For the post-stimulus time window particularly, we suggest that these data provide new constraints for (e.g. recurrent) models of vision and visual awareness. Finally, our data are in line with the idea that pre-stimulus masking operates differently from conventional post-stimulus masking.