Kristin W. Flanary & Catherine J. NorrisDartmouth College
Stronger response to large monetary lossesthan gains
adapted from Harinck et al. (2007)2
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You just heard about the negativity bias, which reflects the idea that losses loom larger than gains, at least when dealing with highly emotional stimuli. So for example, if people are presented with the possibility of winning or losing a large amount of money, they show stronger responses to losing the money than winning it. (CLICK)
Stronger response to large monetary lossesthan gains
adapted from Harinck et al. (2007)3
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However, at the opposite end of the spectrum – when values are small – this pattern actually reverses.
Stronger response to small monetary gainsthan losses
adapted from Harinck et al. (2007)4
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That is, people show stronger responses to winning a small amount of money than losing it. So, it seems that gains actually loom larger than losses when dealing with small amounts of money.
Same response biases for subjective measures
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People also show the same kinds of response biases when responding to more subjective emotional events. Research coming out of our lab has replicated Harinck et al. looking at responses to IAPS pictures, and we see the same biases. Participants view pictures ranging from neutral all the way up to very emotional (along the x-axis), and rate how negative and positive they feel about them (along the y-axis). Again, they rate the very negative pictures more strongly than the very positive, but when the pictures are low in emotional value, participants give stronger positive ratings than negative. It is this bias toward more positive responding at low levels of emotional input that we call the positivity offset. So, why is the positivity offset important? The ESM posits that the PO serves an adaptive function, in that it facilitates approach motivation, so that organisms can explore and engage with new environments. There are also individual differences in the PO which tend to be stable over time, generalize across different types of stimuli, and predict behavior in important ways.
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More positivity when life stages end• Carstensen, Isaacowitz, & Charles (1999)• Carstensen, Fung, & Charles (2003)• Mather & Carstensen (2005)
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One of these kinds of differences may involve age. Laura Carstensen and her colleagues have found a related, but different bias toward positive responding. They have suggested that, as chapters of our lives come to a close, as we near the end of a life stage, we are motivated to feel more positively, as if we are trying to make the most out of the time we have left in that stage. And perhaps the most pertinent end of a life stage is the end of life itself. Consistent with this idea, older adults tend to respond more positively to emotional stimuli than younger adults do.
More positive responses to neutral pictures with older age
van Reekum, Schaefer, Lapate, Norris, Greischar, & Davidson (2010)8
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Given people’s tendency to respond more positively to stimuli with low levels of emotional input, it may be that responses to neutral stimuli are important for the positivity effect in aging. In other words, it may be that older adults respond more positively to stimuli with low levels of emotional value. Consistent with this, Carien van Reekum, in collaboration with Cat, showed adults ranging in age from their 30s all the way to their 80s neutral pictures and measured corrugator activity (an index of valence, so that increased corrugator activity reflects negative affect, and decreased activity reflects positive affect).
More positive responses to neutral pictures with older age
van Reekum, Schaefer, Lapate, Norris, Greischar, & Davidson (2010)9
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They found that corrugator activity decreased as a function of age, suggesting more positive responding to neutral pictures over the lifecourse. Participants also gave (more subjective) ratings of the pictures, and again, they showed more positive responding to neutral pictures with age.
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So, in our study, we wanted to compare positive and negative responses to emotional stimuli in order to see if older adults show a greater positivity offset.
Older (65-80 yrs) and younger females (18-22 yrs)
Viewed 168 IAPS images during fMRI scans• Pictures spanned the valence dimension
Independent positive and negative ratings• Evaluative Space Grid (Larsen et al., 2009)
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To do that, we used…
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Response patterns to the neutral stimuli are a replication of van Reekum et al. What really interesting, though, is this age difference in responses to mild pictures. Older adults show a positivity offset that extends into responses to mildly emotional pictures, while younger adults no longer show a positivity offset to the mild pictures.
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This has 18 older and 19 younger subjects. 2(Age) x 2 (Val: neg, pos) x 2 (Ext: neutral, mild). Val x Ext x Age is not significant (p = .198). It’s marginal in the 2x2x4.
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So we see then, that older adults do indeed show more favorable responses to mild stimuli, and these responses take the form of an extended positivity offset – stronger positive than negative responses to mild, not just neutral, pictures. What, then, can the neural correlates of the PO tell us about the underlying neural mechanisms of these responses to mild stimuli?
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To investigate this question, we looked at responses to just the mild pictures. Using these mild pictures gives us two different groups of pictures (unpleasant, pleasant), and an advantage of that is that we can use those two groups to calculate a contrast.
PObehavior =
PObrain =
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So that what you’re left with is the magnitude of ratings that were stronger for pleasant than unpleasant pictures…the neural activity that was greater to pleasant than unpleasant pictures.
PObrain regressed onto PObehavior• BA 10
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“So if older adults are showing a greater positivity offset, and a greater positivity offset is associated with greater BA 10 activation to unpleasant pictures, the next logical question to ask is whether older adults show greater BA10 activation to these unpleasant pictures.” This picture is with 5 older subjects. BA10 activation also shows up on R, but not at the current threshold (p< .01). Other clusters on this image do not meet cluster size threshold.
PObrain regressed onto PObehavior• BA 10
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“So if older adults are showing a greater positivity offset, and a greater positivity offset is associated with greater BA 10 activation to unpleasant pictures, the next logical question to ask is whether older adults show greater BA10 activation to these unpleasant pictures.” This picture is with 5 older subjects. BA10 activation also shows up on R, but not at the current threshold (p< .01). Other clusters on this image do not meet cluster size threshold.
Older show more BA 10 activation to mildly unpleasant pictures
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So, BA10 activation is negatively correlated with the PO, and older adults show increased BA10 activation to mildly unpleasant pictures. So why does it matter?
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More positivity at end of life stages• Carstensen, Isaacowitz, & Charles (1999)• Carstensen, Fung, & Charles (2003)• Mather & Carstensen (2005)
Emotion regulation as mechanism• Gross et al. (1997)• Carstensen et al. (2003)
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It matters because the theory suggests that emotion regulation is an underlying mechanism of the positivity effect seen in aging. Importantly, BA10 has also been implicated in emotion regulation processes.
Activation in BA 10 in response to down-regulation of negative affect is associated with:
• decreased amygdala and insula activation Urry, van Reekum, et al. (2006), Goldin et al. (2008)
• decreased salivary cortisol levels in older adults Urry, van Reekum, et al. (2006)
Adapted from Urry, van Reekum et al. (2006) 23
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So if older adults are regulating their responses to mildly unpleasant pictures, we might expect them to take longer to rate them, as regulation is often a deliberative process that takes time. To look at this, we next turned to response times for rating the pictures. Check out: Ochsner KN, Ray RD, Cooper JC, et al. For better or for worse: Neural systems supporting the cognitive down- and up-regulation of negative emotion. Neuroimage. 2004;23:483–499. [PubMed] Ochsner KN, Bunge SA, Gross JJ, Gabrieli JD. Rethinking feelings: An FMRI study of the cognitive regulation of emotion. Journal of Cognitive Neuroscience. 2002;14:1215–1229. [PubMed] Beauregard M, Levesque J, Bourgouin P. Neural correlates of conscious self-regulation of emotion. J Neurosci. 2001;21:RC165. [PubMed] Levesque J, Eugene F, Joanette Y, et al. Neural circuitry underlying voluntary suppression of sadness. Biol Psychiatry. 2003;53:502–10. [PubMed] Be aware of other possible functions, too. Brede Database (32 63 6): memory encoding; unpleasant > neutral; Other functions: default network (Buckner et al,2008); mentalizing about (dissimilar) others (Mitchell et al., 2006; Lieberman, 2007; Dovidio et al., 2008); increasing negative affect (e.g., empathy; Lieberman, 2007)
Older slower to mildly unpleasant
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And we see that older adults do indeed show longer response times when rating the unpleasant pictures. Again, if older adults are regulating their responses to the unpleasant pictures, we might also expect them to rate them with increasing positivity the longer they take to make a rating.
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Older:r = .58, R2 = .34, p = .01
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So next we looked at the relationship between positive ratings of unpleasant pictures and response times. This has 18 older subjects. No extreme outliers.
This graph represents our stimulus selection, and as you can see, we chose stimuli from across the whole valence continuum. There are 3 categories of pleasant pictures – mild, moderate, and extreme, 3 categories of unpleasant pictures, and a group of neutral pictures in between. The categories are matched for social content. The filled in shapes represent pictures containing social content, and the empty shapes are nonsocial. Each of the corresponding categories are matched in arousal and extremity, and all the pictures are matched for visual qualities, such as luminance, RGB values, spatial complexity, etc.
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This graph represents our stimulus selection, and as you can see, we chose stimuli from across the whole valence continuum. There are 3 categories of pleasant pictures – mild, moderate, and extreme, 3 categories of unpleasant pictures, and a group of neutral pictures in between. The categories are matched for social content. The filled in shapes represent pictures containing social content, and the empty shapes are nonsocial. Each of the corresponding categories are matched in arousal and extremity, and all the pictures are matched for visual qualities, such as luminance, RGB values, spatial complexity, etc.
adapted from Larsen et al. (2009)
Positive: 1Negative: 0
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adapted from Larsen et al. (2009)
Positive: 4Negative: 1Ambivalence: 1
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Older show more BA 10 activation to mildly unpleasant pictures
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* p < .0541
Older slower to mildly unpleasant
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Neophilic vs. Neophobic rats• Smaller glucocorticoid responses to novel environment
