Impaired perception of simultaneous stimuli in a patient with posterior cortical atrophy: an attentional account.

We assessed visuospatial abilities in PCA. Sequential display of two simple geometric figures enhanced detection and discrimination relative to simultaneous display (Exps 1 & 2). Comparing edges of a single object enhanced discrimination relative to comparing edges of two separate objects, consistent with object-based attention (Exp. 3). Recognition of complex line drawings was spared for a single object but disrupted by an attention-grabbing small circle (Exp. 4). A covert orienting task showed difficulty disengaging from previous locations and attentional bias toward the right visual field (Exp. 5). These findings shed light on the role of visual attention in perceptual awareness.

Superfluous neuroscience information makes explanations of psychological phenomena more appealing.

Does the presence of irrelevant neuroscience information make explanations of psychological phenomena more appealing? Do fMRI pictures further increase that allure? To help answer these questions, 385 college students in four experiments read brief descriptions of psychological phenomena, each one accompanied by an explanation of varying quality (good vs. circular) and followed by superfluous information of various types. Ancillary measures assessed participants' analytical thinking, beliefs on dualism and free will, and admiration for different sciences. In Experiment 1, superfluous neuroscience information increased the judged quality of the argument for both good and bad explanations, whereas accompanying fMRI pictures had no impact above and beyond the neuroscience text, suggesting a bias that is conceptual rather than pictorial. Superfluous neuroscience information was more alluring than social science information (Experiment 2) and more alluring than information from prestigious "hard sciences" (Experiments 3 and 4). Analytical thinking did not protect against the neuroscience bias, nor did a belief in dualism or free will. We conclude that the "allure of neuroscience" bias is conceptual, specific to neuroscience, and not easily accounted for by the prestige of the discipline. It may stem from the lay belief that the brain is the best explanans for mental phenomena.

Cognitive control: dynamic, sustained, and voluntary influences.

The cost of incongruent stimuli is reduced when conflict is expected. This series of experiments tested whether this improved performance is due to repetition priming or to enhanced cognitive control. Using a paradigm in which Word and Number Stroop alternated every trial, Experiment 1 assessed dynamic trial-to-trial changes. Incongruent trials led to task-specific reduction of conflict (trial n + 2) without cross-task modulation (trial n + 1), but this was fully explained by repetition priming. In contrast, an increased ratio of incongruent words did lead to sustained task-specific enhancement, above and beyond repetition priming (Experiment 2). Experiments 3 and 4 assessed the voluntary modulation of cognitive control: A cue predicted the congruency of the incoming trial, allowing participants to establish the correct mindset (Word Stroop in Experiment 3, Flanker task in Experiment 4). Preparing oneself to process an incongruent word (or flanker) enhanced conflict resolution in the subsequent Number Stroop, an example of cross-task modulation. Taken together, these experiments reveal the multifaceted aspects of conflict resolution: Trial-to-trial changes are often due to repetition priming; sustained modulations brought about by task demands are task specific; and voluntary modulations are task general.

Attentional networks in normal aging and Alzheimer's disease.

By combining a flanker task and a cuing task into a single paradigm, the authors assessed the effects of orienting and alerting on conflict resolution and explored how normal aging and Alzheimer's disease (AD) modulate these attentional functions. Orienting failed to enhance conflict resolution; alerting was most beneficial for trials without conflict, as if acting on response criterion rather than on information processing. Alerting cues were most effective in the older groups--healthy aging and AD. Conflict resolution was impaired only in AD. Orienting remained unchanged across groups. These findings provide evidence of different life span developmental and clinical trajectories for each attentional network.

Impaired recognition of negative facial emotions in patients with frontotemporal dementia.

Patients with behavioral variant of frontotemporal dementia (FTD) have difficulties recognizing facial emotions, a deficit that may contribute to their impaired social skills. In three experiments, we investigated the FTD deficit in recognition of facial emotions, by comparing six patients with impaired social conduct, nine Alzheimer's patients, and 10 age-matched healthy adults. Experiment 1 revealed that FTD patients were impaired in the recognition of negative facial emotions. Experiment 2 replicated these findings when participants had to determine whether two faces were expressing the same or different emotions. Experiment 3 was a control study in which participants had to discriminate whether two faces were of the same sex. In this non-emotional processing task, both patient groups performed worse than normal participants, but FTD patients performed as well as Alzheimer's patients. We conclude that FTD patients are impaired in the recognition of negative facial emotions.

Common Sense Beliefs about the Central Self, Moral Character, and the Brain.

To assess lay beliefs about self and brain, we probed people's opinions about the central self, in relation to morality, willful control, and brain relevance. In study 1, 172 participants compared the central self to the peripheral self. The central self, construed at this abstract level, was seen as more brain-based than the peripheral self, less changeable through willful control, and yet more indicative of moral character. In study 2, 210 participants described 18 specific personality traits on 6 dimensions: centrality to self, moral relevance, willful control, brain dependence, temporal stability, and desirability. Consistent with Study 1, centrality to the self, construed at this more concrete level, was positively correlated to brain dependence. Centrality to the self was also correlated to desirability and temporal stability, but not to morality or willful control. We discuss differences and similarities between abstract (Study 1) and concrete (Study 2) levels of construal of the central self, and conclude that in contemporary American society people readily embrace the brain as the underlying substrate of who they truly are.

Converging evidence for the detection of change without awareness.

In this chapter, we explore the possibility that changes can be registered by the visual system and can influence behavior even in the absence of conscious awareness. We begin by describing the basic phenomenon of change blindness, introduce a framework for discussing some of the key issues relating to change detection as a whole, and then examine the main lines of evidence that point to the existence of implicit change detection.

Explicit mechanisms do not account for implicit localization and identification of change: An empirical reply to Mitroff et al. (2002).

Several recent findings support the notion that changes in the environment can be implicitly represented by the visual system. S. R. Mitroff, D. J. Simons, and S. L. Franconeri (see record 2002-15293-003) challenged this view and proposed alternative interpretations based on explicit strategies. Across 4 experiments, the current study finds no empirical support for such alternative proposals. Experiment 1 shows that subjects do not rely on unchanged items when locating an unaware change. Experiments 2 and 3 show that unaware changes affect performance even when they occur at an unpredictable location. Experiment 4 shows that the unaware congruency effect does not depend simply on the pattern of the final display. The authors point to converging evidence from other methodologies and highlight several weaknesses in Mitroff et al's theoretical arguments. It is concluded here that implicit representation of change provides the most parsimonious explanation for both past and present findings. ((c) 2003 APA, all rights reserved)

Juicio y toma de decisiones en niños de edad escolar / Judgment and Decision Making in School-Age Children

En los últimos cincuenta años, psicólogos y economistas han catalogado los errores que la gente adulta comete cuando toma decisiones. El objetivo de nuestro resumen narrativo es describir estos errores como ocurren en niños de edad escolar. Luego de una breve introducción a las teorías más importantes en economía comportamental (Utilidad Esperada, Prospect, Rastro Difuso, Proceso Dual) haremos un resumen de esta literatura, con énfasis en el período de edad escolar. Evaluamos si los niños comprenden el concepto de 'valor esperado', si sus respuestas cambian en base a como se hace la pregunta, y si prefieren arriesgar en vez de aceptar propuestas seguras. También describimos, desde una perspectiva del desarrollo, la tendencia a sobrevalorar las posesiones, a perseverar cuando el gasto es irrecuperable, y a tener diferentes cuentas mentales. Nuestra revisión indica que las tendencias que se ven en la adultez también suelen ocurrir en niños y niñas de edad escolar, y señala áreas en las que se carece de datos sólidos. Concluimos nuestro artículo sugiriendo futuras áreas de investigación

Over the last half century, psychologists and behavioral economists have catalogued myriad mistakes that people make when making decisions. The way those mistakes are expressed in school-aged children is the focus of this narrative review. After a brief introduction to the main theoretical positions (expected utility theory, prospect theory, fuzzy-trace theory, dual-systems theory), we do a comprehensive review of the developmental literature. We start with children's understanding of expected value, their sensitivity to framing effects, and their tendency to favor risky choices over riskless options. Next, we describe developmental research on the endowment effect, sunk cost, and mental accounting. Our review indicates that biases observed in adults are often evident in school-age children too, and singles out areas of developmental research in which solid information is not available. We conclude by highlighting areas in need of future research

Empathy in frontotemporal dementia and Alzheimer's disease.

Using naturalistic stimuli, we assessed the ability to infer what other people are feeling in three groups of participants: healthy elderly adults, patients suffering from the behavioral variant of frontotemporal dementia (FTD-b), and patients suffering from Alzheimer's disease (AD). After watching videotaped interviews of everyday people (nonactors) discussing an emotionally relevant event in their lives, participants answered questions regarding the interviewee's feelings. Both patient groups inferred emotions as accurately as the healthy elderly, provided the emotions were displayed unambiguously and consistently across the interview. However, when the displayed emotions became more variable and ambiguous, performance in both patient groups became impaired relative to healthy elderly participants. The similar profile across the two clinical groups despite their differences in social skills suggests that nonsocial cognitive processes affected in dementia may be an important factor in drawing inferences about other people's feelings.

False-belief understanding in frontotemporal dementia and Alzheimer's disease.

The ability to understand other people's behavior in terms of mental states, such as beliefs, desires, and intentions, is central to social interaction. It has been argued that the interpersonal problems of patients with behavioral variant of frontotemporal dementia (FTD-b) are due to a dysfunction of that system. We used first- and second-order false-belief tasks to assess theory-of-mind reasoning in a group of patients with FTD-b and a cognitively matched group of patients with Alzheimer's disease (AD). Both patient groups were equally impaired relative to a healthy elderly group in the cognitively demanding second-order false-belief tasks, revealing that cognitive demands are an important factor in false-belief task performance. Both patient groups reached ceiling performance in the first-order false-belief tasks with minimal cognitive demands, despite the striking difference in their social graces. These results suggest that a conceptual deficit in theory of mind-as measured by the false-belief task-is not at the core of the differences between FTD-b and AD.

Selective attention in early Dementia of Alzheimer Type.

This study explored possible deficits in selective attention brought about by Dementia of Alzheimer Type (DAT). In three experiments, we tested patients with early DAT, healthy elderly, and young adults under low memory demands to assess perceptual filtering, conflict resolution, and set switching abilities. We found no evidence of impaired perceptual filtering nor evidence of impaired conflict resolution in early DAT. In contrast, early DAT patients did exhibit a global cost in set switching consistent with an inability to maintain the goals of the task (mental set). We discuss these findings in relation to the DAT literature on executive attention, dual-tasking, and working memory.

Representation of change: separate electrophysiological markers of attention, awareness, and implicit processing.

Awareness of change within a visual scene only occurs in the presence of focused attention. When two versions of a complex scene are presented in alternating sequence separated by a blank mask, unattended changes usually remain undetected, although they may be represented implicitly. To test whether awareness of change and focused attention had the same or separable neurophysiological substrates, and to search for the neural substrates of implicit representation of change, we recorded event-related brain potentials (ERPs) during a change blindness task. Relative to active search, focusing attention in the absence of a change enhanced an ERP component over frontal sites around 100-300 msec after stimulus onset, and in posterior sites at the 150-300 msec window. Focusing attention to the location of a change that subjects were aware of, replicated those attentional effects, but also produced a unique positive deflection in the 350-600 msec window, broadly distributed with its epicenter in mediocentral areas. The unique topography and time course of this latter modulation, together with its dependence on the aware perception of change, distinguishes this "awareness of change" electrophysiological response from the electrophysiological effects of focused attention. Finally, implicit representation of change elicited a distinct electrophysiological event: Unaware changes triggered a positive deflection at the 240-300 msec window, relative to trials with no change. Overall, the present data suggest that attention, awareness of change, and implicit representation of change may be mediated by separate underlying systems.