Decline and Compensation in Aging Brain and Cognition: Promises and Constraints

Age-related cognitive declines are common and inevitable, but life trajectories of brain and cognitive functions are variable and plastic. To identify the mechanisms of decline, the prospects for improvement, and the constraints on the remedial approaches, the contributors of this special issuer examine several diverse areas of cognitive and brain aging: from structural and metabolic brain aging to genetics, and from age-sensitive cognitive domains to those that resist aging. In spite of such thematic diversity, several common threads are clear. To achieve better compensation for age-related changes in cognition, we need to understand their brain substrates, telling cognitively relevant from epiphenomenal. We also need to understand the sources of profound individual variability in aging trajectories, and to learn to tailor interventions to specific individual profiles of decline.     

Habituation and sensitization of acoustic startle: opposite influences of dopamine D1 and D2-family receptors

The startle response evoked by repeated presentation of a loud acoustic stimulus is regulated by the independent processes of sensitization and habituation. While schizophrenia is associated with information processing impairments, there is conflicting evidence regarding the existence of habituation deficits in schizophrenic patients. Recent clinical evidence, however, indicates that patients with schizophrenia display exaggerated startle sensitization and diminished habituation. Given the linkage between dopaminergic abnormalities and schizophrenia, the goal of the present investigation was to examine the effect of deleting D₁ and D₂-like dopamine receptors on sensitization and habituation of the acoustic startle reflex in mice. For these experiments, the acoustic startle reflex was assessed in dopamine D₁, D₂, and D₃ receptor wild-type (WT) and knockout (KO) mice on a C57BL/6J background, using a methodology that can measure both sensitization and habituation. Mice lacking the D₁ receptor gene displayed enhanced sensitization, along with a decrease in the amount of habituation that occurs in response to repetitive presentations of a startling stimulus. Conversely, the loss of the dopamine D₂ or D₃ receptor gene produced a sensitization deficit and a significant increase in habituation. The behavioral phenotype exhibited by D₁ receptor KO mice is clearly distinct from that of the D₂ and D₃ receptor KO mice. The findings in D₁ receptor KO mice are reminiscent of the abnormalities observed in schizophrenic patients tested in comparable startle paradigms, and indicate that D₁ agonists may possess therapeutic efficacy against the information processing deficits associated with schizophrenia.     

Intuition: Dumb But Lucky. Fortuitous Affective Cues and Their Disruption by Analytic Thought

'Intuition' can sometimes produce attitudes and judgments that are superior to those generated from conscious, analytic thinking. I consider two unsatisfying explanations for the differences: (i) that reasoning is 'dumb', in that it simply limits and biases otherwise adequate decisions; or (ii) that intuition is 'smart', in that it improves those processes by invoking qualitatively distinct and sophisticated cognitive mechanisms. I propose, instead, that intuition is 'dumb but lucky', that its positive benefits are achieved via fortuitious covariation, often inherent in the structure of the social world, between decision outcomes and subjective feeling states – particularly positive affect, familiarity, and cognitive fluency. I also advance the 'affect disruption hypothesis', which proposes that analytic thinking interferes with the use of these affective cues by underweighting affective responses, conflating feeling states that are subjectively similar, and/or generating competing emotions. I review data in support of this hypothesis in domains such as art preferences, music popularity, and sports prediction, and provide a new characterization of what constitutes 'good intuition'.     

Does lack of control lead to conspiracy beliefs? A meta-analysis

Perceived lack of control is widely believed to motivate, at least partly, belief in conspiracy theories. We question the theoretical foundations of this belief and meta-analyze existing published and unpublished studies to assess the overall effect of lack of control on conspiracy beliefs. The overall effect was small and not statistically significant (d = −0.05), and was not moderated by comparison group (baseline vs. control affirmation), type of manipulation used to threaten control, inclusion of a manipulation check, or sample type. However, the predicted effect of control was more likely to be observed when beliefs were measured in terms of specific conspiracy theories, rather than as general or abstract claims. Overall, the present studies to date offer limited support for the hypothesis that conspiracy beliefs arise as a compensatory control.     

The attractiveness of nonface averages: implications for an evolutionary explanation of the attractiveness of average faces

Researchers have argued that humans' attraction to average faces reflects an evolved psychological mechanism to identify high-quality mates. If this direct-selection account is correct, there is no reason to expect a similar averageness bias for stimuli that are irrelevant to reproductive fitness. The current study, however, found a strong relationship between averageness and attractiveness for dogs, wristwatches, and birds. The most parsimonious explanation is that humans have a general attraction to prototypical exemplars, and that their attraction to average faces is a reflection of this more general attraction. We tested whether a general preference for familiar stimuli can account for the attractiveness of averageness. This account was not supported for dogs or birds, but could not be ruled out for watches.     

Aptitude-related differences in auditory information processing: effects of selective attention and tone duration

College students selected for high or low aptitude performed an auditory backward recognition masking task in which tones differed in pitch (770 or 870 Hz) and duration (10, 13 or 20 msec). Ss were required to attend selectively to the pitch but not to the duration of the targets. As predicted, higher aptitude was associated with lower recognition thresholds at all tone durations. Although increased attentional demands impaired recognition thresholds, this had no apparent differential effect on aptitude-related differences in auditory information processing.     

Foxhole atheism,revisited: The effects of mortality salience on explicit and implicit religious belief

Although fear of death features prominently in many historical and contemporary theories as a major motivational factor in religious belief, the empirical evidence available is ambivalent, and limited, we argue, by imprecise measures of belief and insufficient attention to the distinction between implicit and explicit aspects of cognition. The present research used both explicit (questionnaire) and implicit (single-target implicit association test; property verification) measurement techniques to examine how thoughts of death influence, specifically, belief in religious supernatural agents. When primed with death, participants explicitly defended their own religious worldview, such that self-described Christians were more confident that supernatural religious entities exist, while non-religious participants were more confident that they do not. However, when belief was measured implicitly, death priming increased all participants' beliefs in religious supernatural entities, regardless of their prior religious commitments. The results are interpreted in terms of a dual-process model of religious cognition, which can be used to resolve conflicting prior data, as well as to help explain the perplexing durability of religious belief.     

Improving performance and increasing the use of non-positive testing in a rule-discovery task

A well-documented characteristic of rule discovery behaviour is subjects' infrequent use of negative testing. Previous attempts at increasing the use of negative testing have met with little success. In an evaluation task, we found that subjects appreciate the benefits of negative testing and disconfirmation (Kareev & Halberstadt, this issue). Further, when given the choice, subjects prefer to begin their inquiry by employing a reception mode of inquiry, and only later switch to a generative strategy (Halberstadt & Kareev, 1992). In the present study we had subjects solve two rule-discovery problems. For the training problem, 180 subjects were assigned either to the traditional generation mode, in which subjects had to generate number triplets, or to a reception mode, in which subjects were presented with number triplets by the experimenter. For the subsequent test problem both groups used the traditional generation mode. Results revealed that subjects trained by the reception mode were more likely to use non-positive tests and more likely to solve the second problem. Apparently, training under the less demanding reception mode enabled subjects to realize the potential relevance of nonpositive testing.     

Evaluating negative tests and refutations in a rule discovery task

Subjects participating in Wason's rule discovery task (1960) overwhelmingly try to confirm rather than refute their currently held hypothesis. Such a strategy is often inadequate and runs counter to the canons of scientific methodology. The present study was designed to investigate subjects' differential evaluation of test strategies and outcome. One-hundred and sixty students participated in two experiments in which they had to judge someone else's potential test items in Wason's task. Experiment 1 demonstrated that exposure to various histories has a mediating effect on the strength of the confirmation bias. In Experiment 2, subjects knew the researcher's rule and thus whether each proposed test item would lead to confirmation or refutation of the hypothesis under consideration. The preferred items were those that alerted the subject to an incorrect hypothesis (refutation) and those that turned out to be positive instances of the rule sought after, with the combination of the two (a negative test leading to refutation) being most highly evaluated.     

Transitions between Modes of Inquiry in a Rule Discovery Task

Scientists obtain their knowledge about the world through one of two major modes of inquiry—observation of naturally occurring phenomena and active experimentation. Both modes of inquiry have been extensively researched in studies of hypothesis testing behaviour and scientific inquiry, the first in studies employing the reception paradigm, the second in studies employing the selection/generation paradigm. The prevalence of both paradigms and their correspondence to well-established modes of scientific inquiry led to the hypothesis that subjects, if allowed, would employ both modes of inquiry. The variables affecting the choice of one mode rather than the other and the transitions between the two modes were expected to shed new light on the process of scientific inquiry. To test this hypothesis, 27 adults and 27 eighth-graders were set three rule-discovery problems, in a computer environment that allowed free transitions between item reception and generation. Item generation was significantly more prevalent in the adult sample, but almost all the adults and approximately half the children employed both modes of inquiry in at least one problem. When both modes of inquiry were employed, the reception mode tended to precede the generation mode. An inverse relationship was observed between item generation and the proportion of positive instances supplied by the environment. Individual inquiry styles were evident in both age groups. These results call attention to the need for a theory incorporating both modes of inquiry as integral components of the inquiry process. They also demonstrate the utility of empirical investigations that let subjects freely choose which mode to employ at any point of the inquiry process.