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Don’t Sweat the Small Stuff: Age Differences in the Positivity Offset Kristin W. Flanary & Catherine J. Norris Dartmouth College Introduction Method Participants: • Younger (18-22 years) and older (65-80 years) females recruited from Dartmouth College (younger) and the surrounding community (older) Design: ● 168 IAPS (Lang, Bradley, & Cuthbert, 2005) pictures filled 7 valence categories (24 pictures each): neutral; mildly, moderately, and very negative; and mildly, moderately, and very positive ● Pictures were matched on social content, visual properties and (female only) normative ratings of arousal and extremity. Results: Response Times Discussion Correspondence may be addressed to: [email protected] Results: Emotional Biases References R Results: Whole-Brain Regression E16 Procedure: ● Participants viewed IAPS pictures during fMRI scans ● Following the fMRI task, participants rated each picture on both positivity and negativity (0-4) using the Evaluative Space Grid (ESG; Larsen, Norris, McGraw, Hawkley & Cacioppo, 2009) Behavioral Analysis: Picture ratings were submitted to a 2 (Age: older, younger) x 2 (Valence: unpleasant, pleasant) x 4 (Extremity: neutral, mild, moderate, extreme) repeated- measures ANOVA Positive: 1 Negative: 0 Cacioppo, J. T., Gardner, W. L., & Berntson, G. G. (1997). Beyond bipolar conceptualizations and measures: The case of attitudes and evaluative space. Personality and Social Psychology Review, 1, 3-25. Lang, P. J., Bradley, M. M., & Cuthbert, B. N. (2005). International affective picture system (IAPS): Instruction manual and affective ratings. Technical Report A-6, The Center for Research in Psychophysiology, University of Florida. Larsen, J., Norris, C., McGraw, A., Hawkley, L., & Cacioppo, J. (2009). The evaluative space grid: A single-item measure of positivity and negativity. Cognition & Emotion , 23, 453-480. Norris, C.J., Gollan, J., Berntson, G.G. & Cacioppo, J.T. (2010). The current structure of research on evaluative space. Biological Psychology, 84, 422-436. Mather, M. & Carstensen, L.L. (2005). Aging and motivated cognition: The positivity effect in attention and memory. Trends in Cognitive Science, 9, 496-502. Urry, H.L., van Reekum, C.M., Johnstone, T., Kalin, N.H., Thurow, M.E. et al. (2006). Amygdala and ventromedial prefrontal cortex are inversely coupled during regulation of negative affect and predict the diurnal pattern of cortisol secretion among older adults. The Journal of Neuroscience, 26, 4415-4425. van Reekum, C.M., Schaefer, S.M., Lapate, R.C., Norris, C.J., Greischer, L.L., et al. (2010). Aging is associated with positive responding to neutral information but reduced recovery from negative information. Social Cognitive and Affective Neuroscience. doi:10.1093/scan/nsq03 0 0.5 1 1.5 2 2.5 3 3.5 4 Neu Mild Mod Very Dominant Ratings Older Pleasant Unpleasant 0 0.5 1 1.5 2 2.5 3 3.5 4 Neu Mild Mod Very Dominant Ratings Younger Pleasant Unpleasant Picture ratings supported the predictions of the ESM, showing a significant Valence x Extremity interaction, F(3,33) = 50.31, p < .001, such that neutral and mildly pleasant pictures elicited a stronger response than unpleasant pictures (i.e., a positivity offset), and moderately and very unpleasant pictures elicited a stronger response than pleasant pictures (i.e., a negativity bias). Compared to younger adults, older adults showed an extended positivity offset and no difference in the negativity bias, F(3,33) = 9.53, p < .001. The greater positivity offset exhibited by older adults was associated with responses to mildly unpleasant pictures: • Greater BA 10 activation • Slower response times • More positive ratings as a function of response time Results suggest that: • The positivity effect may be due in part to a greater positivity offset. • Older adults may be regulating their responses to mildly unpleasant stimuli in an attempt to “find the silver lining” (see Urry et al., 2006). The Evaluative Space Model (ESM; Norris et al., 2010; Cacioppo, Gardner & Berntson, 1997) holds that positivity and negativity are separable and can vary independently. Accordingly, the ESM predicts a negativity bias in extremely emotional stimuli, in which stronger responses are elicited by very unpleasant than very pleasant stimuli. It also predicts a positivity offset in mildly emotional stimuli, such that stronger responses are elicited by mildly pleasant than mildly unpleasant stimuli. Negativity Positivity Stimulus Intensity low high Response Strength P O NB Figure 1. Theoretical predictions of the Evaluative Space Model (Norris et al., 2010; Cacioppo, Gardner & Berntson, 1997) Older adults (e.g, 65-80 yrs) have demonstrated a “positivity effect” such that older adults seem more predisposed toward positivity than younger adults (e.g, Mather & Carstensen, 2005). However, the underlying mechanisms of the positivity effect remains unclear. van Reekum et al. (2010) found that adults demonstrated increased positive responding to neutral stimuli with older age. Thus, an increased positivity offset may be one underlying mechanism of the positivity effect seen in aging. This study directly compared positive and negative responses to emotional stimuli in order to investigate 1) whether older adults show an increased positivity offset relative to younger adults, and 2) the neural mechanisms underlying this increased positivity offset. r = p < .01, corrected (33, -61, -5) Pleas - Unpl (BA 10) Pleas – Unpl (ratings) P > UP P > UP UP > P UP > P -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 Mildly Unpleasant Mildly Pleasant Mean AUC % Signal Change Older Younger -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Mildly Unpleasant Mildly Pleasant Response Time z-scores Older Younger fMRI Data Acquisition and Analysis: ● A full set of 36 axial slices (3.5mm thick, 0.5mm gap, interleaved) was collected on a Philips 3.0 T Achieva Intera scanner every 2 s (TR = 2000 ms, TE = 35 ms, flip angle = 90°, FOV = 24 cm, 80 x 80 matrix size, fat suppressed). ● Positivity offset (PO) scores for picture ratings and neural activation were calculated (mildly pleasant – mildly unpleasant) for use in a whole-brain voxel-wise regression analysis. PO neural was regressed on PO ratings, predicting a neural PO from the behavioral PO. PO ratings scores were negatively correlated with a cluster in left BA 10, r = -.83, p < .001. That is, greater PO ratings scores were associated with greater BA 10 activation to mildly unpleasant than mildly pleasant pictures. Data extracted from BA 10 were submitted to a 2 (Age: older, younger) x 2 (Valence: mildly unpleasant, mildly pleasant) repeated-measures ANOVA. A significant Age x Valence interaction, F(1,15) = 8.06, p = .01, indicated that, compared to younger adults, older adults showed greater BA 10 activation to mildly unpleasant pictures. Response times were also submitted to a 2 (Age: older, younger) x 2 (Valence: mildly unpleasant, mildly pleasant) repeated-measures ANOVA . A significant Age x Valence interaction revealed that older adults took longer to rate mildly unpleasant pictures than younger adults, F(1,35) = 5.95, p < .05. Moreover, older adults showed a positive correlation between response times and positive ratings of mildly unpleasant pictures, r = .58, p = .01. That is, the longer older adults took to rate mildly unpleasant pictures, the more positively they rated them. Positive Ratings z-scored Response Times Mildly Unpleasant
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