Neurocomputational mechanisms of adaptive learning in social exchanges.

Prior work on prosocial and self-serving behavior in human economic exchanges has shown that counterparts' high social reputations bias striatal reward signals and elicit cooperation, even when such cooperation is disadvantageous. This phenomenon suggests that the human striatum is modulated by the other's social value, which is insensitive to the individual's own choices to cooperate or defect. We tested an alternative hypothesis that, when people learn from their interactions with others, they encode prediction error updates with respect to their own policy. Under this policy update account striatal signals would reflect positive prediction errors when the individual's choices correctly anticipated not only the counterpart's cooperation but also defection. We examined behavior in three samples using reinforcement learning and model-free analyses and performed an fMRI study of striatal learning signals. In order to uncover the dynamics of goal-directed learning, we introduced reversals in the counterpart's behavior and provided counterfactual (would-be) feedback when the individual chose not to engage with the counterpart. Behavioral data and model-derived prediction error maps (in both whole-brain and a priori striatal region of interest analyses) supported the policy update model. Thus, as people continually adjust their rate of cooperation based on experience, their behavior and striatal learning signals reveal a self-centered instrumental process corresponding to reciprocal altruism.

Pathways to Late-Life Suicidal Behavior: Cluster Analysis and Predictive Validation of Suicidal Behavior in a Sample of Older Adults With Major Depression.

OBJECTIVE: Clinical heterogeneity is a key challenge to understanding suicidal risk, as different pathways to suicidal behavior are likely to exist. We aimed to identify such pathways by uncovering latent classes of late-life depression cases and relating them to prior and future suicidal behavior. METHODS: Data were collected from June 2010 to September 2015. In this longitudinal study we examined distinct associations of clinical and cognitive/decision-making factors with suicidal behavior in 194 older (50+ years) nondemented, depressed patients; 57 nonpsychiatric healthy controls provided benchmark data. The DSM-IV was used to establish diagnostic criteria. We identified multivariate patterns of risk factors, defining clusters based on personality traits, perceived social support, cognitive performance, and decision-making in an analysis blinded to participants' history of suicidal behavior. We validated these clusters using past and prospective suicidal ideation and behavior. RESULTS: Of 5 clusters identified, 3 were associated with high risk for suicidal behavior: (1) cognitive deficits, dysfunctional personality, low social support, high willingness to delay future rewards, and overrepresentation of high-lethality attempters; (2) high-personality pathology (ie, low self-esteem), minimal or no cognitive deficits, and overrepresentation of low-lethality attempters and ideators; (3) cognitive deficits, inability to delay future rewards, and similar distribution of high- and low-lethality attempters. There were significant between-cluster differences in number (P < .001) and lethality (P = .002) of past suicide attempts and in the likelihood of future suicide attempts (P = .010, 30 attempts by 22 patients, 2 fatal) and emergency psychiatric hospitalizations to prevent suicide (P = .005, 31 participants). CONCLUSIONS: Three pathways to suicidal behavior in older patients were found, marked by (1) very high levels of cognitive and dispositional risk factors suggesting a dementia prodrome, (2) dysfunctional personality traits, and (3) impulsive decision-making and cognitive deficits.

Perceived burdensomeness is associated with low-lethality suicide attempts, dysfunctional interpersonal style, and younger rather than older age.

OBJECTIVES: Perceived burdensomeness is thought to contribute to suicide risk. However, suicidal behavior is clinically and psychologically heterogeneous. Does a high level of perceived burdensomeness differentiate medically serious suicidal acts, most closely resembling death by suicide, from less serious ones? How is perceived burdensomeness related to dysfunctional personality dimensions implicated in suicide? We sought to answer these questions in a cross-sectional, case-control study of adults, aged 42 years or older (n = 165). METHODS: Participants were suicidal depressed with history of high-lethality and low-lethality attempts, depressed with serious suicidal ideation, depressed non-suicidal, and psychiatrically healthy controls. Following detailed clinical characterization, we assessed perceived burdensomeness, the Big Five, impulsivity, and anger rumination. RESULTS: Low-lethality attempters reported the highest levels of perceived burdensomeness, followed by ideators, high-lethality attempters, non-suicidal depressed, and healthy controls. Group differences were robust to confounders, including demographics, severity of depression, and physical illness burden. In suicide attempters, perceived burdensomeness scaled positively with neuroticism, impulsivity, and anger and negatively with extraversion, conscientiousness, and age. CONCLUSIONS: Our findings suggest that perceived burdensomeness is most prominent in a subgroup of younger individuals with lower-lethality suicide attempts and a dysfunctional interpersonal style. Older adults with high-lethality attempts are surprisingly more resilient to the feelings of burdensomeness. Copyright © 2016 John Wiley & Sons, Ltd.

Decision-making competence and attempted suicide.

OBJECTIVE: The propensity of people vulnerable to suicide to make poor life decisions is increasingly well documented. Do they display an extreme degree of decision biases? The present study used a behavioral-decision approach to examine the susceptibility of low-lethality and high-lethality suicide attempters to common decision biases that may ultimately obscure alternative solutions and deterrents to suicide in a crisis. METHOD: We assessed older and middle-aged (42-97 years) individuals who made high-lethality (medically serious) (n = 31) and low-lethality suicide attempts (n = 29). Comparison groups included suicide ideators (n = 30), nonsuicidal depressed participants (n = 53), and psychiatrically healthy participants (n = 28). Attempters, ideators, and nonsuicidal depressed participants had nonpsychotic major depression (DSM-IV criteria). Decision biases included sunk cost (inability to abort an action for which costs are irrecoverable), framing (responding to superficial features of how a problem is presented), underconfidence/overconfidence (appropriateness of confidence in knowledge), and inconsistent risk perception. Data were collected between June 2010 and February 2014. RESULTS: Both high- and low-lethality attempters were more susceptible to framing effects as compared to the other groups included in this study (P ≤ .05, ηp2 = 0.06). In contrast, low-lethality attempters were more susceptible to sunk costs than both the comparison groups and high-lethality attempters (P ≤ .01, ηp2 = 0.09). These group differences remained after accounting for age, global cognitive performance, and impulsive traits. Premorbid IQ partially explained group differences in framing effects. CONCLUSIONS: Suicide attempters' failure to resist framing may reflect their inability to consider a decision from an objective standpoint in a crisis. Failure of low-lethality attempters to resist sunk cost may reflect their tendency to confuse past and future costs of their behavior, lowering their threshold for acting on suicidal thoughts.

Impulsive traits and unplanned suicide attempts predict exaggerated prefrontal response to angry faces in the elderly.

OBJECTIVE: Abnormal responses to social stimuli are seen in people vulnerable to suicidal behavior, indicating possible disruptions in the neural circuitry mediating the interpretation of socioemotional cues. These disruptions have not been empirically related to psychological and cognitive pathways to suicide. In the present study of older suicide attempters, we examined neural responses to emotional faces and their relationship to impulsivity, one of the components of the suicidal diathesis. METHODS: Using functional magnetic resonance imaging, we recorded neurohemodynamic responses to angry faces in a carefully characterized sample of 18 depressed elderly with history of suicide attempts, 13 depressed nonsuicidal patients, and 18 healthy individuals, all aged 60+. Impulsivity was assessed with the Social Problem Solving Inventory Impulsivity/Carelessness Style subscale and Barratt Impulsiveness Scale. The Suicide Intent Scale planning subscale was used to describe the degree of planning associated with the most lethal attempt. RESULTS: Depression and history of attempted suicide were not associated with neural responses to angry faces, failing to replicate earlier studies. Higher impulsivity, however, predicted exaggerated responses to angry faces in fronto-opercular and dorsomedial prefrontal cortex (pcorr <0.05). Poorly planned suicide attempts also predicted increased fronto-opercular responses. Results were robust to effects of medication exposure, comorbid anxiety and addiction, severity of depression, burden of physical illness, and possible brain injury from suicide attempts. CONCLUSION: Impulsive traits and history of unplanned suicide attempts partly explain the heterogeneity in neural responses to angry faces in depressed elderly. Displays of social emotion command excessive cortical processing in impulsive suicide attempters.

The emergence of frequency effects in eye movements.

A visual search experiment employed strings of Landolt Cs to examine how the gap size of and frequency of exposure to distractor strings affected eye movements. Increases in gap size were associated with shorter first-fixation durations, gaze durations, and total times, as well as fewer fixations. Importantly, both the number and duration of fixations decreased with repeated exposures. The findings provide evidence for the role of cognition in guiding eye-movements, and a potential explanation for word-frequency effects observed in reading.

Serial or parallel? Using depth-of-processing to examine attention allocation during reading.

This paper presents an experiment investigating attention allocation in four tasks requiring varied degrees of lexical processing of 1-4 simultaneously displayed words. Response times and eye movements were only modestly affected by the number of words in an asterisk-detection task but increased markedly with the number of words in letter-detection, rhyme-judgment, and semantic-judgment tasks, suggesting that attention may not be serial for tasks that do not require significant lexical processing (e.g., detecting visual features), but is approximately serial for tasks that do (e.g., retrieving word meanings). The implications of these results for models of readers' eye movements are discussed.

The adaptive character of the attentional system: statistical sensitivity in a target localization task.

A localization task required participants to indicate which of 4 locations contained a briefly displayed target. Most displays also contained a distractor that was not equally probable in these locations, affecting performance dramatically. Responses were faster when a display had no distractor and almost as fast when the distractor was in its frequent location. Conversely, responses were slower when targets appeared in frequent-distractor locations, even thou targets were equally likely in each location. Negative-priming effects were reliably smaller when targets followed distractors in the frequent-distractor location compared to the rare-distractor location, challenging the episodic-retrieval account Experiment 2 added a 5th location that rarely displayed distractors and never targets, yet responses slowed most when distractors appeared there. The results confirmed that the attentional system is sensitive to first- and higher-order statistical patterns and can make short- and long-term adjustments in preferences based on prior history of inspecting unsuccessful locations.