Date Published: January 6, 2017
Publisher: Public Library of Science
Author(s): Leslie A. Zebrowitz, Jasmine Boshyan, Noreen Ward, Angela Gutchess, Nouchine Hadjikhani, Gilles van Luijtelaar.
An older adult positivity effect, i.e., the tendency for older adults to favor positive over negative stimulus information more than do younger adults, has been previously shown in attention, memory, and evaluations. This effect has been attributed to greater emotion regulation in older adults. In the case of attention and memory, this explanation has been supported by some evidence that the older adult positivity effect is most pronounced for negative stimuli, which would motivate emotion regulation, and that it is reduced by cognitive load, which would impede emotion regulation. We investigated whether greater older adult positivity in the case of evaluative responses to faces is also enhanced for negative stimuli and attenuated by cognitive load, as an emotion regulation explanation would predict. In two studies, younger and older adults rated trustworthiness of faces that varied in valence both under low and high cognitive load, with the latter manipulated by a distracting backwards counting task. In Study 1, face valence was manipulated by attractiveness (low /disfigured faces, medium, high/fashion models’ faces). In Study 2, face valence was manipulated by trustworthiness (low, medium, high). Both studies revealed a significant older adult positivity effect. However, contrary to an emotion regulation account, this effect was not stronger for more negative faces, and cognitive load increased rather than decreased the rated trustworthiness of negatively valenced faces. Although inconsistent with emotion regulation, the latter effect is consistent with theory and research arguing that more cognitive resources are required to process negative stimuli, because they are more cognitively elaborated than positive ones. The finding that increased age and increased cognitive load both enhanced the positivity of trustworthy ratings suggests that the older adult positivity effect in evaluative ratings of faces may reflect age-related declines in cognitive capacity rather than increases in the regulation of negative emotions.
Considerable evidence has demonstrated an older adult (OA) positivity effect in attention and memory, although meta-analyses reveal that the effect is small [1–3]. Specifically, whereas younger adults (YA) tend to show preferential attention to and retrieval of negatively valenced faces, words, and pictures, OA do not show this negative bias and sometimes favor positively valenced stimuli [4–6]. There is also some evidence for a positivity effect in evaluative ratings of both neutral expression faces [7, 8] and emotion expression faces [9, 10]. These age differences may have significant social consequences given that first impressions from faces predict voting preferences and judicial decisions, among other socially important judgments . The aims of the present research were to investigate whether OA positivity in evaluative ratings of neutral expression faces is moderated by cognitive load and by the valence of the faces, as manipulated by variations in facial attractiveness or trustworthiness. As discussed below, such moderation would support an emotion regulation explanation for this OA positivity effect.
We performed a 2 (Rater age:) x 2 (Rater sex) x 2 (Distraction) x 3 (Face Valence) repeated measures ANOVA, with face valence and distraction manipulated within subjects. Means and standard deviations are presented in Table 2. We also performed a planned interaction contrast  to test the specific prediction that the linear effect of face valence would differ by rater age. Another planned interaction contrast tested the 3-way interaction prediction that distraction would decrease rating positivity for OA, while increasing it for YA and that this effect would be most pronounced for negatively valenced faces. In addition, significant main effects were followed by simple effects comparisons to determine whether the overall effect held true in all conditions. Although we included rater sex in the analysis to account for any variance it might contribute, none of the effects of rater age, face valence, and distraction reported below were moderated by rater sex, and we do not report any other rater sex effects, as we had no predictions regarding this variable.
Consistent with the attractiveness halo effect, low attractive, disfigured faces were rated as less trustworthy than average or high attractive faces. The fact that the latter two categories did not differ in perceived trustworthiness is consistent with some evidence that the halo effect reflects ‘ugly is bad’ more strongly than it reflects ‘beautiful is good’ . Consistent with previous research on age differences in evaluations of faces [7, 8], there was an OA positivity effect, with OA rating the faces as more trustworthy than did YA. Given that the unattractive faces in the present study were markedly deformed, one would expect OA positivity to be most pronounced for these faces if it derived from the motivation to regulate negative emotions. However, the age x face interaction effect was not significant either in the omnibus test or in a planned contrast. Moreover, simple effects comparisons revealed that the age difference main effect in rating positivity was significant only for faces medium in attractiveness. Although inconsistent with emotion regulation, this result is consistent with the finding that emotional reactivity shown in facial expressions when viewing various stimuli revealed greater OA positivity for neutrally valenced, but not positively or negatively valenced stimuli . The restriction of the OA positivity effect to medium attractive faces also is consistent with evidence that OA positivity in memory is shown for non-arousing but not for emotionally arousing words, be they positive or negative . The images of disfigured individuals, who comprised our low attractive faces, and the fashion models, who comprised our high attractive faces, are arguably more arousing than images of ordinary individuals, who comprised our medium attractive faces. Even though high attractive faces were not rated as more trustworthy than the medium ones, the highly attractive faces may nevertheless have been more arousing. On this account, the restriction of the OA positivity effect to ratings of medium faces may be one instance of a tendency for that effect to be absent for strongly valenced or arousing stimuli. In the case of stimuli with a strong negative valence, this exception is inconsistent with an emotion regulation explanation for the OA positivity effect. Future research that directly assesses participants’ assessments of how arousing the faces are or their emotional responses to the faces would be useful to confirm this qualification to the OA positivity effect in evaluations.
The means and standard deviations for trustworthy ratings in each condition are reported in Table 4. The analyses were identical to those performed in Study 1. As in Study 1, we do not report effects of Rater Sex as this variable did not moderate any of the predicted effects reported below.
The results of the present study replicate and qualify previous evidence for an OA positivity effect in evaluative ratings of faces, and they argue against an emotion regulation explanation for this effect. Greater OA positivity was shown for trustworthy ratings of faces with positive, medium, or negative valence in Study 2 as well as for faces with a medium valence in Study 1. These effects are consistent with previous evidence for an OA positivity effect in trait ratings, including trustworthiness, for a representative sample of faces . The pattern of greater OA positivity did not, however, extend to those faces with an extreme valence likely to elicit high arousal. These results are consistent with the finding that OA positivity in retrieval was shown for low, but not high arousal words , and it suggests that other research documenting the positivity effect in attention and memory may have done so only because low arousal stimuli were included in addition to high arousal stimuli [15, 16, 24, 25]. On the other hand, these results are not consistent with an emotion regulation explanation for OA positivity effects in evaluative ratings of faces, as emotion regulation processes should yield the strongest OA positivity effect for the extremely negative deformed faces in Study 1 and the more negatively valenced low trustworthy faces in Study 2, which we did not find.
Our results replicate and qualify previous evidence for an OA positivity effect in evaluative ratings of faces. Most notably, we find that the effect is absent for faces that are disfigured or highly attractive, suggesting that highly arousing stimuli do not elicit age differences in evaluative positivity just as they may not elicit such differences in recall . Future research that directly assesses participants’ emotional responses when evaluating faces or other stimuli would be useful to confirm this qualification to the OA positivity effect in evaluations. This qualification, coupled with the finding that cognitive load increased rather than decreased positivity for OA, argues against an emotion regulation explanation for the age differences in evaluative ratings. Specifically, high cognitive load would decrease emotion regulation capacity and should therefore decrease OA positivity if emotion regulation were the mechanism. Our results also rule out age differences in visual abilities as an explanation for greater OA positivity, as the poorer vision of OA suppressed rather than mediated the OA positivity effect. The parallel effects of cognitive load and age on positivity, coupled with evidence for a negative relationship between processing speed and positivity within the older adult group, suggests that lower cognitive capacity may contribute to the OA positivity effect in evaluations of faces. This possibility clearly merits further study with additional measures of cognitive capacity. There is also a need for additional research to evaluate the possibility that there is a dissociation in the mechanism that accounts for OA positivity effects in attention, and memory vs. evaluations, with emotion regulation playing a more significant role in the first two effects. Other possible mediating mechanisms also merit attention.