Annual Review of Psychology - Volume 66, 2015

Our own experiences, as well as the findings of many studies, suggest that emotionally arousing experiences can create lasting memories. This autobiographical article provides a brief summary of the author's research investigating neurobiological systems responsible for the influence of emotional arousal on the consolidation of lasting memories. The research began with the finding that stimulant drugs enhanced memory in rats when administered shortly after training. Those findings suggested the possibility that endogenous systems activated by arousal might influence neural processes underlying memory consolidation. Subsequent findings that adrenal stress hormones activated by learning experiences enhance memory consolidation provided strong evidence supporting this hypothesis. Other findings suggest that the enhancement is induced by stress hormone activation of the amygdala. The findings also suggest that the basolateral amygdala modulates memory consolidation via its projections to brain regions involved in processing different aspects and forms of memory. This emotional-arousal-activated neurobiological system thus seems to play an important adaptive role in insuring that the strength of our memories will reflect their emotional significance.

Nearly 40 years of research on the function of the nucleus accumbens (NAc) has provided a wealth of information on its contributions to behavior but has also yielded controversies and misconceptions regarding these functions. A primary tenet of this review is that, rather than serving as a “reward” center, the NAc plays a key role in action selection, integrating cognitive and affective information processed by frontal and temporal lobe regions to augment the efficiency and vigor of appetitively or aversively motivated behaviors. Its involvement in these functions is most prominent when the appropriate course of action is ambiguous, uncertain, laden with distractors, or in a state of flux. To this end, different subregions of the NAc play dissociable roles in refining action selection, promoting approach toward motivationally relevant stimuli, suppressing inappropriate actions so that goals may be obtained more efficiently, and encoding action outcomes that guide the direction of subsequent ones.

New neurons continue to be generated in the dentate gyrus throughout life, providing this region of the hippocampus with exceptional structural plasticity, but the function of this ongoing neurogenesis is unknown. Inhibition of adult neurogenesis produces some behavioral impairments that suggest a role for new neurons in learning and memory; however, other behavioral changes appear inconsistent with this function. A review of studies investigating the function of the hippocampus going back several decades reveals many ideas that seem to converge on a critical role for the hippocampus in stress response and emotion. These potential hippocampal functions provide new avenues for investigating the behavioral functions of adult neurogenesis. And, conversely, studies in animals lacking adult neurogenesis, which are likely to have more limited and more specific impairments than are seen with lesions, may provide valuable new insights into the function of the hippocampus. A complete understanding of the function of the hippocampus must explain its role in emotion and the relationship between its emotional and memory functions.

Research on cognitive control and executive function has long recognized the relevance of motivational factors. Recently, however, the topic has come increasingly to center stage, with a surge of new studies examining the interface of motivation and cognitive control. In the present article we survey research situated at this interface, considering work from cognitive and social psychology and behavioral economics, but with a particular focus on neuroscience research. We organize existing findings into three core areas, considering them in the light of currently vying theoretical perspectives. Based on the accumulated evidence, we advocate for a view of control function that treats it as a domain of reward-based decision making. More broadly, we argue that neuroscientific evidence plays a critical role in understanding the mechanisms by which motivation and cognitive control interact. Opportunities for further cross-fertilization between behavioral and neuroscientific research are highlighted.

For more than 50 years, psychologists and neuroscientists have recognized the importance of a working memory to coordinate processing when multiple goals are active and to guide behavior with information that is not present in the immediate environment. In recent years, psychological theory and cognitive neuroscience data have converged on the idea that information is encoded into working memory by allocating attention to internal representations, whether semantic long-term memory (e.g., letters, digits, words), sensory, or motoric. Thus, information-based multivariate analyses of human functional MRI data typically find evidence for the temporary representation of stimuli in regions that also process this information in nonworking memory contexts. The prefrontal cortex (PFC), on the other hand, exerts control over behavior by biasing the salience of mnemonic representations and adjudicating among competing, context-dependent rules. The “control of the controller” emerges from a complex interplay between PFC and striatal circuits and ascending dopaminergic neuromodulatory signals.

Sleep has a critical role in promoting health. Research over the past decade has documented that sleep disturbance has a powerful influence on the risk of infectious disease, the occurrence and progression of several major medical illnesses including cardiovascular disease and cancer, and the incidence of depression. Increasingly, the field has focused on identifying the biological mechanisms underlying these effects. This review highlights the impact of sleep on adaptive and innate immunity, with consideration of the dynamics of sleep disturbance, sleep restriction, and insomnia on (a) antiviral immune responses with consequences for vaccine responses and infectious disease risk and (b) proinflammatory immune responses with implications for cardiovascular disease, cancer, and depression. This review also discusses the neuroendocrine and autonomic neural underpinnings linking sleep disturbance and immunity and the reciprocal links between sleep and inflammatory biology. Finally, interventions are discussed as effective strategies to improve sleep, and potential opportunities are identified to promote sleep health for therapeutic control of chronic infectious, inflammatory, and neuropsychiatric diseases.

A continuing debate in language acquisition research is whether there are critical periods (CPs) in development during which the system is most responsive to environmental input. Recent advances in neurobiology provide a mechanistic explanation of CPs, with the balance between excitatory and inhibitory processes establishing the onset and molecular brakes establishing the offset of windows of plasticity. In this article, we review the literature on human speech perception development within the context of this CP model, highlighting research that reveals the interplay of maturational and experiential influences at key junctures in development and presenting paradigmatic examples testing CP models in human subjects. We conclude with a discussion of how a mechanistic understanding of CP processes changes the nature of the debate: The question no longer is, “Are there CPs?” but rather what processes open them, keep them open, close them, and allow them to be reopened.

Visual perceptual learning (VPL) is long-term performance increase resulting from visual perceptual experience. Task-relevant VPL of a feature results from training of a task on the feature relevant to the task. Task-irrelevant VPL arises as a result of exposure to the feature irrelevant to the trained task. At least two serious problems exist. First, there is the controversy over which stage of information processing is changed in association with task-relevant VPL. Second, no model has ever explained both task-relevant and task-irrelevant VPL. Here we propose a dual plasticity model in which feature-based plasticity is a change in a representation of the learned feature, and task-based plasticity is a change in processing of the trained task. Although the two types of plasticity underlie task-relevant VPL, only feature-based plasticity underlies task-irrelevant VPL. This model provides a new comprehensive framework in which apparently contradictory results could be explained.

Causal knowledge plays a crucial role in human thought, but the nature of causal representation and inference remains a puzzle. Can human causal inference be captured by relations of probabilistic dependency, or does it draw on richer forms of representation? This article explores this question by reviewing research in reasoning, decision making, various forms of judgment, and attribution. We endorse causal Bayesian networks as the best normative framework and as a productive guide to theory building. However, it is incomplete as an account of causal thinking. On the basis of a range of experimental work, we identify three hallmarks of causal reasoning—the role of mechanism, narrative, and mental simulation—all of which go beyond mere probabilistic knowledge. We propose that the hallmarks are closely related. Mental simulations are representations over time of mechanisms. When multiple actors are involved, these simulations are aggregated into narratives.

The well-respected tradition of research on concepts uses cross-cultural comparisons to explore which aspects of conceptual behavior are universal versus culturally variable. This work continues, but it is being supplemented by intensified efforts to study how conceptual systems and cultural systems interact to modify and support each other. For example, cultural studies within the framework of domain specificity (e.g., folkphysics, folkpsychology, folkbiology) are beginning to query the domains themselves and offer alternative organizing principles (e.g., folksociology, folkecology). Findings highlight the multifaceted nature of both concepts and culture: Individuals adopt distinct conceptual construals in accordance with culturally infused systems such as language and discourse, knowledge and beliefs, and epistemological orientations. This picture complicates questions about cognitive universality or variability, suggesting that researchers may productively adopt a systems-level approach to conceptual organization and cultural epistemologies. Related implications for diversity in cognitive science are discussed.

For decades, the dominant paradigm for studying decision making—the expected utility framework—has been burdened by an increasing number of empirical findings that question its validity as a model of human cognition and behavior. However, as Kuhn (1962) argued in his seminal discussion of paradigm shifts, an old paradigm cannot be abandoned until a new paradigm emerges to replace it. In this article, we argue that the recent shift in researcher attention toward basic cognitive processes that give rise to decision phenomena constitutes the beginning of that replacement paradigm. Models grounded in basic perceptual, attentional, memory, and aggregation processes have begun to proliferate. The development of this new approach closely aligns with Kuhn's notion of paradigm shift, suggesting that this is a particularly generative and revolutionary time to be studying decision science.

Adolescence is the transition from childhood to adulthood that begins around the onset of puberty and ends with relative independence from the parent. This developmental period is one when an individual is probably stronger, of higher reasoning capacity, and more resistant to disease than ever before, yet when mortality rates increase by 200%. These untimely deaths are not due to disease but to preventable deaths associated with adolescents putting themselves in harm's way (e.g., accidental fatalities). We present evidence that these alarming health statistics are in part due to diminished self-control—the ability to inhibit inappropriate desires, emotions, and actions in favor of appropriate ones. Findings of adolescent-specific changes in self-control and underlying brain circuitry are considered in terms of how evolutionarily based biological constraints and experiences shape the brain to adapt to the unique intellectual, physical, sexual, and social challenges of adolescence.

Humans exhibit a suite of biases when making economic decisions. We review recent research on the origins of human decision making by examining whether similar choice biases are seen in nonhuman primates, our closest phylogenetic relatives. We propose that comparative studies can provide insight into four major questions about the nature of human choice biases that cannot be addressed by studies of our species alone. First, research with other primates can address the evolution of human choice biases and identify shared versus human-unique tendencies in decision making. Second, primate studies can constrain hypotheses about the psychological mechanisms underlying such biases. Third, comparisons of closely related species can identify when distinct mechanisms underlie related biases by examining evolutionary dissociations in choice strategies. Finally, comparative work can provide insight into the biological rationality of economically irrational preferences.

Over the past 20 years, the field of cognitive neuroscience has relied heavily on hemodynamic measures of blood oxygenation in local regions of the brain to make inferences about underlying cognitive processes. These same functional magnetic resonance imaging (fMRI) and functional near-infrared spectroscopy (fNIRS) techniques have recently been adapted for use with human infants. We review the advantages and disadvantages of these two neuroimaging methods for studies of infant cognition, with a particular emphasis on their technical limitations and the linking hypotheses that are used to draw conclusions from correlational data. In addition to summarizing key findings in several domains of infant cognition, we highlight the prospects of improving the quality of fNIRS data from infants to address in a more sophisticated way how cognitive development is mediated by changes in underlying neural mechanisms.

The efficacy of interventions might be underestimated or even go undetected as a main effect when it is hidden in gene-by-environment (G×E) interactions. This review moves beyond the problems thwarting correlational G×E research to propose genetic differential susceptibility experiments. G×E experiments can test the bright side as well as the dark side of the moderating role of genotypes traditionally considered to represent vulnerability to negative conditions. The differential susceptibility model predicts that carriers of these risk genotypes profit most from interventions changing the environment for the better. The evolutionary background of G×E and differential susceptibility is discussed, and statistical methods for the analysis of differential susceptibility (versus diathesis stress) are reviewed. Then, based on results from 22 randomized G×E experiments, meta-analytic evidence for the differential susceptibility model is presented. Intervention effects are much stronger in the susceptible genotypes than in the nonsusceptible genotypes. The final sections suggest possibilities to broaden the G component in the G×E equation by including genetic pathways, and to broaden the E component by including methylation level and gene expression as promising ways to probe the concept of the environment more deeply and address the perennial issue of what works for whom.

The socioeconomic and cultural changes that result from an increasingly interconnected world have been speculated to have important implications for the nature of adolescent development. Unfortunately, the historical time necessary for these changes to take place means that definitive research on the impact of globalization necessarily will be slow in forthcoming. Adolescents from immigrant families, however, already experience the social and cultural shifts thought to typify globalization, and an analysis of their experiences could shed light on what to expect as existing national barriers become more permeable. The value of flexibility in the face of great social and cultural change appears to be the dominant theme from research on immigrant youth, although that flexibility can be constrained by socioeconomic, ethnic, and racial stratification systems in host societies. This review highlights the implications of these findings for what may lie ahead for teenagers as globalization continues to expand.

Health and nutritional risks co-occur in the lives of children under the age of 2 years who live in developing countries. We review evidence showing how these risks, in addition to inadequate psychosocial stimulation, prevent children from developing expected cognitive and language abilities. A systematic review and meta-analysis of 21 interventions aimed at enhancing stimulation and 18 interventions that provided better nutrition—all conducted since 2000—revealed that stimulation had a medium effect size of 0.42 and 0.47 on cognitive and language development, respectively, whereas nutrition by itself had a small effect size of 0.09. The implementation processes of these interventions are described and compared. A number of unresolved issues are outlined and discussed, including ways to maximize parental health behavior change, assess mediators that account for intervention effects, and expand the assessment of young children's brain functions that underlie language and cognition and are affected by nutrition and stimulation.

Progress in treating and preventing mental disorders may follow from research that integrates development, genetics, and neuroscience. This review first delineates how longitudinal research has identified three particular groups of disorders shown to differ on the basis of symptom trajectories and risk-factor profiles. In the next section, the review describes how research on genetic contributions to psychopathology has elucidated the nature of risk for two groups of disorders, the neurodevelopmental and psychotic disorders. In the third section, the review describes how research on environmental contributions to psychopathology has targeted early temperament, its associated perturbations in information-processing functions, and its relations to a third group of disorders, the emotional disorders. For all three groups of disorders, such integrative research has generated ideas about novel interventions. The hope is that over the coming decade such ideas will lead to novel treatments that alter the trajectory of risk in developmental psychopathology.

Conscious experience is fluid; it rarely remains on one topic for an extended period without deviation. Its dynamic nature is illustrated by the experience of mind wandering, in which attention switches from a current task to unrelated thoughts and feelings. Studies exploring the phenomenology of mind wandering highlight the importance of its content and relation to meta-cognition in determining its functional outcomes. Examination of the information-processing demands of the mind-wandering state suggests that it involves perceptual decoupling to escape the constraints of the moment, its content arises from episodic and affective processes, and its regulation relies on executive control. Mind wandering also involves a complex balance of costs and benefits: Its association with various kinds of error underlines its cost, whereas its relationship to creativity and future planning suggest its potential value. Although essential to the stream of consciousness, various strategies may minimize the downsides of mind wandering while maintaining its productive aspects.