Extent of food restriction affects probability but not delay-based decision-making

Rodent studies on decision-making often use food rewards and food-restrict subjects in order to motivate performance. However, food restriction has widespread effects on brain and behavior, which depend on factors including extent of restriction and feeding schedule. These factors are well recognized for their effects on motivation, but may also cause effects on decision-making independent of motivation. We examined how the degree of weight-based food restriction in rats influenced decision-making on the probability and delay discounting tasks. Additionally, we examined how the method of food restriction (consistent amount vs. time constrained feeding schedule) influenced decision-making. Our results showed that the degree of weight-based food restriction significantly altered probability, but not delay discounting, and that these effects were not entirely explainable by differences in motivation. Additionally, the method of food restriction did not significantly influence discounting when animals were within the same range of weight-based restriction. Together, our findings suggest that the degree of food restriction may modulate the neural circuitry responsible for selective aspects of decision-making related to probability. Further, these data support the need for tight control and reporting of weight and feeding in studies relying on food restriction, and suggest that the effects of food restriction may be broader than previously considered.     

Our Immigration and Human Rights Work Group in Action: Psychoanalysts Evaluating Asylum Seekers,Trauma and Family Devastation

ABSTRACT

This paper presents the story of a family of four refugees from Central America seeking asylum in the United States, and of the experience of a group of psychoanalysts, members of the New York University Postdoctoral Program Immigration and Human Rights Work Group, who evaluated each member of the family and wrote affidavits in support of their applications for asylum. The work described provides an example of how clinicians can apply their skills and understandings outside the consulting room to address the dire needs of refugees who have fled from their homes. We discuss the process of refugees seeking asylum and the role of a psychological evaluation in the asylum process. We elaborate on the content and process of the evaluations of each member of the family with a focus on the trauma suffered and its sequelae on two school-aged children, their adolescent aunt, and their courageous and protective mother. We also address the analysts’ experience of doing psychological evaluations and writing affidavits for asylum seekers who have experienced trauma.     

Prior knowledge and exemplar frequency

New concepts can be learned by statistical associations, as well as by relevant existing knowledge. We examined the interaction of these two processes by manipulating exemplar frequency and thematic knowledge and considering their interaction through computational modeling. Exemplar frequency affects category learning, with high-frequency items learned more quickly than low-frequency items, and prior knowledge usually speeds category learning. In two experiments in which both of these factors were manipulated, we found that the effects of frequency are greatly reduced when stimulus features are linked by thematic prior knowledge and that frequency effects on single stimulus features can actually be reversed by knowledge. We account for these results with the knowledge resonance model of category learning (Rehder & Murphy, 2003) and conclude that prior knowledge may change representations so that empirical effects, such as those caused by frequency manipulations, are modulated.     

In the mood to face the facts: When a positive mood promotes systematic processing of self-threatening information

Two experiments tested the hypothesis that a positive mood can increase attendance to, and systematic processing of, threatening health information, particularly when the information is self-relevant. In Study 1, a positive mood increased differentiation between strong and weak arguments in a threatening health message about RSI only for participants who had received false feedback regarding their high vulnerability to RSI. Mood had no effects under conditions of low vulnerability. In Study 2, a positive mood speeded up responses to self-threatening words—compared with neutral words—for smokers who had just read a threatening health message about smoking. The authors conclude that fostering a positive mood may promote attendance to and systematic processing of information that threatens the self, and hence contribute to the success of health campaigns targeted at individuals who are vulnerable to specific health risks.

Context Effects on Musical Chord Categorization: Different Forms of Top‐Down Feedback in Speech and Music?

A critical issue in perception is the manner in which top-down expectancies guide lower level perceptual processes. In speech, a common paradigm is to construct continua ranging between two phonetic endpoints and to determine how higher level lexical context influences the perceived boundary. We applied this approach to music, presenting participants with major/minor triad continua after brief musical contexts. Two experiments yielded results that differed from classic results in speech perception. In speech, context generally expands the category of the expected stimuli. We found the opposite in music: The major/minor boundary shifted toward the expected category, contracting it. Together, these experiments support the hypothesis that musical expectancy can feed back to affect lower-level perceptual processes. However, it may do so in a way that differs fundamentally from what has been seen in other domains.     

Mindless resistance to persuasion: Low self‐control fosters the use of resistance‐promoting heuristics

In our consumer society, people are confronted on a daily basis with unsolicited persuasion attempts. The present research challenges the prevailing view that resisting persuasion is more likely to fail when consumers have low self‐control. Four experiments tested the hypothesis that impaired self‐regulation may actually facilitate resistance to persuasion when the influence context contains resistance‐promoting heuristics. Indeed, participants with low self‐control were less likely to comply with a persuasive request (Experiments 1 and 3), reported a less favourable attitude towards an advertised product (Experiment 2), and generated more negative responses towards a persuasive message (Experiment 4) than participants with high self‐control, when they could rely on resistance‐promoting heuristics: a violation of the norm of reciprocity (Experiments 1 and 3), an advertisement disclaimer (Experiment 2), or negative social proof (Experiment 4). Together, these studies demonstrate that contextual cues can bolster resistance when one does not carefully scrutinize an influence attempt.     

The temporal organization of functional brain connectivity is abnormal in schizophrenia but does not correlate with symptomatology

Previous work employing graph theory and nonlinear analysis has found increased spatial and temporal disorder, respectively, of functional brain connectivity in schizophrenia. We present a new method combining graph theory and nonlinear techniques that measures the temporal disorder of functional brain connections. Multichannel electroencephalographic data were windowed and functional networks were reconstructed using the minimum spanning trees of correlation matrices. Using a method based on Shannon entropy, we found elevated connection entropy in gamma activity of patients with schizophrenia; however, gamma connection entropy remained elevated in patients with schizophrenia even after a reduction in symptoms due to treatment with antipsychotics. Our results are consistent with several possibilities: (1) aberrant functional connectivity is epiphenomenal to schizophrenia, (2) aberrant functional connectivity is a central feature but antipsychotics reduce symptoms by an independent mechanism, or (3) connection entropy is not an appropriately sensitive measure of brain abnormalities in schizophrenia.     

Semantic priming is affected by real-time phonological competition: Evidence for continuous cascading systems

Lexical-semantic access is affected by the phonological structure of the lexicon. What is less clear is whether such effects are the result of continuous activation between lexical form and semantic processing or whether they arise from a more modular system in which the timing of accessing lexical form determines the timing of semantic activation. This study examined this issue using the visual world paradigm by investigating the time course of semantic priming as a function of the number of phonological competitors. Critical trials consisted of high or low density auditory targets (e.g., horse) and a visual display containing a target, a semantically related object (e.g., saddle), and two phonologically and semantically unrelated objects (e.g., chimney, bikini). Results showed greater magnitude of priming for semantically related objects of low than of high density words, and no differences for high and low density word targets in the time course of looks to the word semantically related to the target. This pattern of results is consistent with models of cascading activation, which predict that lexical activation has continuous effects on the level of semantic activation, with no delays in the onset of semantic activation for phonologically competing words.