Age-related differences in social economic decision making: the ultimatum game

OBJECTIVES

Despite recognition of the increasing influence of emotion on decision making with age, there are few studies that have assessed older adults' financial choices in a socioemotional context. Thus, social economic decision making between same- versus other-aged partners was assessed.

METHOD

Young (n = 35) and older (n = 34) adults participated in two Ultimatum Games. In the first, they proposed divisions of money between themselves and future young and older participants. In the second, they accepted or rejected fair and unfair divisions of money proposed by past young and older participants. Lastly, participants reported their anger in response to the offers that were proposed to them in the second game.

RESULTS

In the first game, older participants divided the money more generously than did young participants. In the second game, young, but not older, participants rejected more unfair offers proposed by young relative to older adults. However, both participant age groups reported being angrier at unfair offers proposed by young adults compared with when receiving the same offer from an older adult.

DISCUSSION

These findings are discussed in the context of evidence for improved anger regulation and increased prosocial behavior with age.

Functional connectivity between amygdala and facial regions involved in recognition of facial threat

The recognition of threatening faces is important for making social judgments. For example, threatening facial features of defendants could affect the decisions of jurors during a trial. Previous neuroimaging studies using faces of members of the general public have identified a pivotal role of the amygdala in perceiving threat. This functional magnetic resonance imaging study used face photographs of male prisoners who had been convicted of first-degree murder (MUR) as threatening facial stimuli. We compared the subjective ratings of MUR faces with those of control (CON) faces and examined how they were related to brain activation, particularly, the modulation of the functional connectivity between the amygdala and other brain regions. The MUR faces were perceived to be more threatening than the CON faces. The bilateral amygdala was shown to respond to both MUR and CON faces, but subtraction analysis revealed no significant difference between the two. Functional connectivity analysis indicated that the extent of connectivity between the left amygdala and the face-related regions (i.e. the superior temporal sulcus, inferior temporal gyrus and fusiform gyrus) was correlated with the subjective threat rating for the faces. We have demonstrated that the functional connectivity is modulated by vigilance for threatening facial features.

Statistical learning as a basis for social understanding in children

Many authors have argued that infants understand goals, intentions, and beliefs. We posit that infants' success on such tasks might instead reveal an understanding of behaviour, that infants' proficient statistical learning abilities might enable such insights, and that maternal talk scaffolds children's learning about the social world as well. We also consider which skills and insights are likely to be innate, and why it is difficult to say exactly when children understand mental states as opposed to behaviours.

The stature of boys is inversely correlated to the levels of their sertoli cell hormones: do the testes restrain the maturation of boys?

The testes of preadolescent boys appear to be dormant, as they produce only trace levels of testosterone [1]. However, they release supra-adult levels of Müllerian Inhibiting Substance (MIS, anti-Müllerian hormone) and lesser levels of inhibin B (InhB), for unknown reasons [2], [3]. Boys have a variable rate of maturation, which on average is slower than girls. The height of children relative to their parents is an index of their maturity [4], [5]. We report here that a boy's level of MIS and InhB is stable over time and negatively correlates with his height and his height relative to his parent's height. This suggests that boy's with high levels of MIS and InhB are short because they are immature, rather than because they are destined to be short men. The levels of MIS and InhB in the boys did not correlate with known hormonal modulators of growth, and were additive with age and the growth hormone/IGF1 axis as predictors of a boy's height. If MIS and InhB were causal regulators of maturity, then the inter-boy differences in the levels of these hormone produces variation in maturation equivalent to 18-months of development. MIS and InhB may thus account for most of the variation in the rate of male development. If boys lacked these hormones, then an average 5-year-old boy would be over 5 cm taller than age-matched girls, making boys almost as dimorphic as men, for height. This indicates that boys have a high growth potential that is initially suppressed by their testes. The concept of the childhood testes suppressing an adult male feature appears paradoxical. However, the growth of children requires intergenerational transfer of nutrients. Consequently, the MIS/InhB slowing of male growth may have been historically advantageous, as it would minimizes any sex bias in the maternal cost of early child rearing.

Age-related differences in deception

Young and older participants judged the veracity of young and older speakers' opinions about topical issues. All participants found it easier to judge when an older adult was lying relative to a young adult, and older adults were worse than young adults at telling when speakers were telling the truth versus lying. Neither young nor older adults were advantaged when judging a speaker from the same age group. Overall, older adults were more transparent as liars and were worse at detecting lies, with older adults' worse emotion recognition fully mediating the relation between age group and lie detection failures.

Social understanding: How does it fare with advancing years?

Until recently, theory of mind abilities have received little attention beyond the childhood years. However, pioneering work carried out by Happé, Winner, and Brownell (1998) has opened the doors on a new and exciting area of research that examines theory of mind abilities in later years. Happé et al. reported that theory of mind performance was superior in the elderly. Yet, in direct contrast to these findings, Maylor, Moulson, Muncer, and Taylor (2002) report a decline in theory of mind abilities with advancing years. We used Happé et al.'s task and, like Maylor et al., found a decline in theory of mind abilities in the elderly. Yet this deficit was related to a decline in fluid abilities. We then examined whether deficits in social understanding in the elderly could also be independent of fluid abilities. We used two new tasks; identifying emotions from still photos and identifying emotions and cognitions from video clips. Again we found a decline in social understanding in the elderly, and in this case, the decline was independent of changes in fluid abilities.

Iodine supplementation improves cognition in mildly iodine-deficient children

BACKGROUND

The effects of severe iodine deficiency during critical periods of brain development are well documented. There is little known about the consequences of milder forms of iodine deficiency on neurodevelopment.

OBJECTIVE

The objective was to determine whether supplementing mildly iodine-deficient children with iodine improves cognition.

DESIGN

A randomized, placebo-controlled, double-blind trial was conducted in 184 children aged 10-13 y in Dunedin, New Zealand. Children were randomly assigned to receive a daily tablet containing either 150 microg I or placebo for 28 wk. Biochemical, anthropometric, and dietary data were collected from each child at baseline and after 28 wk. Cognitive performance was assessed through 4 subtests from the Wechsler Intelligence Scale for Children.

RESULTS

At baseline, children were mildly iodine deficient [median urinary iodine concentration (UIC): 63 microg/L; thyroglobulin concentration: 16.4 microg/L]. After 28 wk, iodine status improved in the supplemented group (UIC: 145 microg/L; thyroglobulin: 8.5 microg/L), whereas the placebo group remained iodine deficient (UIC: 81 microg/L; thyroglobulin: 11.6 microg/L). Iodine supplementation significantly improved scores for 2 of the 4 cognitive subtests [picture concepts (P = 0.023) and matrix reasoning (P = 0.040)] but not for letter-number sequencing (P = 0.480) or symbol search (P = 0.608). The overall cognitive score of the iodine-supplemented group was 0.19 SDs higher than that of the placebo group (P = 0.011).

CONCLUSIONS

Iodine supplementation improved perceptual reasoning in mildly iodine-deficient children and suggests that mild iodine deficiency could prevent children from attaining their full intellectual potential. The trial was registered with the Australia New Zealand Clinical Trials Register as ACTRN12608000222347.

Threat perception in mild cognitive impairment and early dementia

Mild cognitive impairment (MCI) and dementia affect many aspects of emotion processing. Even though the ability to detect threat is a particularly important aspect of emotion processing, no study to date has assessed threat perception in either of these groups. The purpose of the present study was to test whether individuals with MCI (n = 38) and mild dementia (n = 34) have difficulty differentiating between faces and situations normatively judged to be either high or low in threat relative to age-matched controls (n = 34). To achieve this aim, all participants completed 2 danger rating tasks that involved viewing and rating high- and low-danger images. It was also assessed whether threat perception was related to cognitive functioning and emotion recognition. The results indicated that all 3 groups were accurately, and comparably, able to differentiate high from low-danger faces. However, the dementia group had difficulties differentiating high from low-danger situations, which reflected a bias to overattribute the level of threat posed by normatively judged nonthreatening situations. This difficulty was related to more general cognitive decline.

EMOTION RECOGNITION DEFICITS IN THE ELDERLY

In two studies, healthy elderly adults were poor at recognizing certain emotions. In study one, an emotion face morphed to express a new emotion. The elderly were impaired when recognizing anger and sadness, whereas no differences were found between the two age groups in recognizing fear or happiness, or in a task requiring reasoning about non=emotion stimuli. In study two, the elderly were impaired when judging which of two faces was more angry, sad, or fearful, but they were not impaired when judging other emotions or when judging which of two beakers was more full. The elderly were also impaired when matching emotion sounds to angry, sad, and disgusted faces, but not to other emotions and not when matching non-emotion (e.g., machine) sounds to machines. Elderly deficits were independent of performance on a task requiring basic face processing (gender recognition). Overall, the results provide support for an age-related decline in the recognition of some emotions that is independent of changes in perceptual abilities, processing speed, fluid IQ, basic face processing abilities, and reasoning about non face stimuli. Recognition of emotion stimuli might be mediated by regions of the brain that are independent from those associated with a more general cognitive decline.

Older adults respond quickly to angry faces despite labeling difficulty

Two experiments examined young-old differences in speed of identifying emotion faces and labeling of emotion expressions. In Experiment 1, participants were presented arrays of 9 faces in which all faces were identical (neutral expression) or 1 was different (angry, sad, or happy). Both young and older adults were faster identifying faces as "different" when a discrepant face expressed anger than when it expressed sadness or happiness, and this was true whether the faces were schematics or photographs of real people. In Experiment 2, participants labeled the Experiment 1 schematic and real faces. Older adults were significantly worse than young when labeling angry schematic faces, and angry and sad real faces. Together, this research indicates no age differences in identifying discrepant angry faces from an array, although older adults do have difficulty choosing the correct emotion label for angry faces.

An experimental investigation of referential looking in free-ranging Barbary macaques (Macaca sylvanus)

The authors examined looking behavior between 15 Barbary macaque (Macaca sylvanus) infants and their mothers in the presence of a rubber snake (experimental period) and in the absence of the snake (control period). Two of the 15 infants looked referentially at their mother in the experimental period. Including both referential and nonreferential looks, the six older infants (aged 5 to 12 months) displayed a higher frequency of looks to mother than nine younger infants (aged 3 to 4.5 months) in the experimental period, but not in the control period. Older infants looked more to the mother in the experimental condition, whereas the younger infants looked more to the mother in the control condition, or looked equally in the two conditions. These results suggest that age is an important factor in determining looking behavior to mother in situations of uncertainty. Compared to hand-reared chimpanzees or human infants tested in standard social referencing paradigms, the infant macaques displayed a low rate of referential looking. Possible explanations for this are discussed. (PsycINFO Database Record (c) 2008 APA, all rights reserved).