Running head: EFFECTS OF EMOTION ON TIME AND NUMBER 1. Fewer Things, Lasting Longer: The Effects of Emotion on Quantity Judgments

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1 Running head: EFFECTS OF EMOTION ON TIME AND NUMBER 1 In Press in Psychological Science Fewer Things, Lasting Longer: The Effects of Emotion on Quantity Judgments Laura N. Young*, Department of Psychology, Boston College Sara Cordes, Department of Psychology, Boston College *Corresponding Author's Contact Information: Laura Young, younglz@bc.edu, Boston College Dept. of Psychology 140 Commonwealth Ave 300 McGuinn Hall Chestnut Hill, MA 02467

2 EFFECTS OF EMOTION ON TIME AND NUMBER 2 Abstract What happens to our perception of time and number under the influence of emotion? Using temporal and numeric bisection tasks, we examined the effects of emotional stimuli (images of angry and happy faces, with neutral face controls) on time and number perception within the same subjects. Each participant also completed baseline temporal and numeric bisection tasks without emotional stimuli. Data showed that emotion altered time and number perception in opposing ways. As in prior studies, durations were overestimated following angry faces relative to neutral, consistent with arousal-modulated time perception theories. In contrast, numerosities were underestimated following both angry and happy faces relative to neutral. In addition, processing of time and number were found to be uncorrelated within subjects. Entirely opposite shifts (overestimation of time and underestimation of number) following emotional stimuli suggest separate cognitive systems for time and number that are differentially influenced by emotion. Keywords: Number, Time, Perception, Emotion, Bisection

3 EFFECTS OF EMOTION ON TIME AND NUMBER 3 Fewer Things, Lasting Longer: The Effects of Emotion on Quantity Judgments While emotion and timing interactions have been extensively examined, the effects of emotion on another important quantitative tracking process, numerical processing, have been unstudied. Temporal processing tasks involving tracking durations of visual stimuli have found that emotional information leads to a subjective dilation or overestimation of duration relative to neutral information (e.g., Angrilli, Cherubini, Pavese, & Manfredini, 1997; Bar-Haim, Kerm, Lamy & Zakay, 2009; Droit-Volet, Brunot, Niedenthal, 2004). Yet, it is entirely unknown how emotions impact numerical estimations in similar conditions. An important distinction underlying this investigation is whether, at their most fundamental levels, time and number are truly separable domains. It has been claimed that they are part of a common magnitude-tracking system (Meck & Church, 1983; Walsh, 2003), and this would suggest that numerical estimates, like temporal ones, should also be increased under the influence of emotion. However, evidence against shared systems (e.g., Dormal, et al., 2006; Agrillo, Ranpura, & Butterworth, 2010), suggests that temporal and numeric processing are separable at a fundamental level. Therefore, it is certainly possible that temporal and numeric processing are each affected by emotion in qualitatively different ways. The aim of this study was to test the effects of emotional stimuli on temporal and numeric processing within the same individuals; and, using a baseline condition without emotional stimuli, to compare processing of time and number within subjects. In doing so, this study serves as the first investigation of the impact of emotional stimuli on numerical processing, while also offering new data to consider in relation to theories of a shared common magnitude system for time and number. Method

4 EFFECTS OF EMOTION ON TIME AND NUMBER 4 Thirty-eight undergraduates (M age=19.2; 14 males) completed both a temporal and numeric computerized bisection task (task order counterbalanced; based on Droit-Volet et al., 2004; Gil & Droit-Volet, 2011). Each task began with 8 training trials in which participants learned to press one key following a small standard value (400 ms presentation of an oval or 4 dots) and another key following a large standard value (1600 ms/16 dots). Participants then completed 42 baseline trials in which they indicated whether intermediate durations or numerosities (logarithmically-spaced values; time: 1270, 1008, 800, 635, 504 ms; number: 13, 10, 8, 6, 5) were closer to the small or the large standard. Numeric stimuli were always presented for 400 milliseconds. Following baseline, participants completed 126 emotion trials, identical to baseline except an emotional face stimulus (neutral, happy, and angry faces from the NimStim set: Tottenham et al., 2009) was presented for 400 milliseconds before the oval/dots presentations. The 54 faces used were chosen as the most similar within emotion category from 96 face stimuli judged by nine raters on intensity, attractiveness, arousal and valence, with angry faces judged as more arousing than happy faces, which were more arousing than neutral faces (F(2,51)=911.80, p<.001). Data Analyses As per Droit-Volet et al. (2004), the proportion of long/large responses at each of the seven values was calculated for each participant for each of the four conditions (baseline, angry, happy, and neutral). Using regressions of the probability of long/large responses on duration/numerosity, the point of subjective equality (PSE; the value at which 50% of responses were long/large) was determined for each participant, for each condition within each task. Results Baseline (no faces)

5 EFFECTS OF EMOTION ON TIME AND NUMBER 5 Normalized PSEs for time were significantly higher than those for number (t(37)=5.48, p<.001) and there was no correlation across tasks (r=.090, p=.590), suggesting that temporal and numeric judgments functioned independently within individual participants. Time Consistent with previous findings (Droit-Volet et al., 2004), participants overestimated durations presented after angry faces compared to durations presented after neutral faces, as evidenced by a lower PSE (see Figure 1). Relative to the neutral PSE (M=938.16, SD=134.41), the angry PSE (M=908.63, SD=118.29) was significantly lower (F(1,37)=5.94, p=.020), with the happy PSE falling in between these (M=932.05, SD=121.02; contrasts of happy and neutral, and happy and angry were non-significant, p>.08). Neutral and baseline (no faces) PSEs were not significantly different (p>.08). Number In contrast to the temporal task, both emotional stimuli (angry and happy) led to underestimation relative to the neutral faces in the number bisection task (Figure 1) (angry PSE (M=8.71, SD=.95) versus neutral PSE (M=8.53, SD=1.04): F(1,37)=4.38, p=.043; happy PSE (M=8.75, SD=.92) versus neutral PSE: F(1,37)=4.87, p=.034; happy PSE versus angry PSE, p>.6). Neutral and baseline PSEs did not differ (p>.6). Discussion Entirely different and opposing patterns of results were observed in the temporal and numeric tasks. Consistent with previous studies (e.g., Gil & Droit-Volet, 2011), durations were overestimated under the influence of emotion (angry faces). In contrast, number was underestimated following angry and happy faces. Opposing shifts in numeric and temporal judgments under the influence of emotion, significantly higher PSEs for time than number, and

6 EFFECTS OF EMOTION ON TIME AND NUMBER 6 the finding of no correlation across modalities suggest separate cognitive systems responsible for tracking time and number. Moreover, the difference in the strength of the effects across emotion categories (i.e., largest effects after emotional faces with highest arousal ratings (angry) for time, and no significant difference between the effects of happy or angry faces for number) implies that the mechanism behind the shifts may differ as well. Whereas the pattern of duration overestimation aligned well with arousal ratings of faces in our task, providing further support for claims of arousal-modulated temporal overestimation (Droit-Volet et al., 2004), the mechanism driving the novel finding of underestimation of numerosities under the influence of emotion is unclear. One possibility is that numeric perception was affected by emotion via effects on attentional focusing. Supporting this is evidence that numeric processing draws heavily upon regions of the brain implicated in maintaining control of visual attention (IPS, e.g., Piazza, Mechelli, Price, Butterworth, 2006; Corbetta & Shulman, 2002); and findings of changes in perceptual ability as a result of effects on attention from emotion (Phelps, Ling, Carrasco, 2006). This possibility, along with the question of why emotion-based effects on attention would lead to seeing fewer things, are ripe for investigation. Acknowledgments We thank Emily Lewis for her assistance in administering this study. Funding was provided by an Alfred P. Sloan Fellowship to S.C.

7 EFFECTS OF EMOTION ON TIME AND NUMBER 7 References Agrillo, C., Ranpura, A., Butterworth, B. (2010). Time and numerosity estimation are independent: Behavioral evidence for two different systems using a conflict paradigm. Cognitive Neuroscience, First published on: March 15, 2010 (ifirst). Angrilli, A., Cherubini, P., Pavese, A., & Manfredini, S. (1997). The influence of affective factors on time perception. Perception & Psychophysics, 59, Corbetta, M. & Shulman, G. L. (2002). Control of goal-directed and stimulus-driven attention in the brain. Nature Reviews: Neuroscience, 3, Craig, A. D. (2009). Emotional moments across time: A possible neural basis for time perception in the anterior insula. Philosophical Transactions of the Royal Society B, 364, Dormal, V., Seron, X. & Pesenti, M. (2006). Numerosity-duration interference: a stroop experiment. Acta Psychologica, 121, Droit-Volet, S., Brunot, S., & Niedenthal, P. M. (2004). Perception of the duration of emotional events. Cognition and Emotion, 18, Droit-Volet, S., Fayolle, S. L. & Gil, S. (2011). Emotion and time perception: effects of filminduced mood. Frontiers in Integrative Neuroscience, 5, 1-9. Gil, S. & Droit-Volet, S. (2011). Time flies in the presence of angry faces depending on the temporal task used! Acta Psychologica, 136, Meck, W. H., and Church, R. M. (1983). A mode-control model of counting and timing processes. Journal of Experimental Psychology: Animal Behavior Processes, 9,

8 EFFECTS OF EMOTION ON TIME AND NUMBER 8 Phelps, E. A., Ling, S., & Carrasco, M. (2006). Emotion facilitates perception and potentiates the perceptual benefits of attention. Psychological Science, 17(4), Piazza, M., Mechelli, A., Price, C. J., & Butterworth, B. (2006). Exact and approximate judgements of visual and auditory numerosity: An fmri study. Brain Research, 1106(1), Tottenham, N., Tanaka, J., Leon, A.C., McCarry, T., Nurse, M., Hare, T.A., Marcus, D.J., Westerlund, A., Casey, B.J., Nelson, C.A. (2009). The NimStim set of facial expressions: Judgments from untrained research participants. Psychiatry Research, 168, Walsh, V. (2003). A theory of magnitude: Common cortical metrics of time, space and quantity. Trends in Cognitive Sciences, 7,

9 EFFECTS OF EMOTION ON TIME AND NUMBER 9 Figure 1. Point of Subjective Equality (PSE) by Emotional Condition for Temporal and Numeric Bisection Tasks Note. N = 38. Error bars indicate standard error. Asterisks indicate a significant difference from neutral. Time: angry PSE was significantly lower than neutral; number: angry and happy PSEs were significantly higher than neutral (all p s <.05).