反应抑制的心理加工模型与神经机制

反应抑制是指抑制不符合当前需要的或不恰当行为反应的能力, 也是执行控制加工的重要成分。解释反应抑制的心理加工模型有两种: 反应与抑制相互独立的赛马模型和交互作用的赛马模型。近年来对反应抑制神经机制的研究表明: 额叶－基底神经节系统内的超直接通路和间接通路可能共同负责对优势反应的抑制, 而额下回、辅助运动区/辅助运动前区和前部扣带回皮层等脑区可能是抑制控制的关键脑区; 反应抑制与反应选择、工作记忆和注意的神经加工之间存在密切联系, 它们的激活脑区既相互重叠, 又相互区别; 右背外侧前额皮层的激活可能反映与抑制任务相关的注意和工作记忆的加工。未来的研究需要将脑损伤、神经功能成像和经颅磁刺激等多种技术结合起来, 进一步阐明上述脑区在反应抑制中的相互作用机制。     

Psychology's limits as a scientific discipline: A personal view

I provided a more personal view of Wachtel's (1980) article. I began by discussing the extent to which my own research program complied with his distinctive recommendations. After offering a different take on the impact of high productivity, I focused on (a) the negative effects of the quest for extramural funding and (b) the positive effects of a better balance between theoretical and empirical contributions. I then turn to some of my own theoretical and empirical studies of the place that theory has in successful science. This research suggests that theory only has a beneficial effect when it is integrative in function and when it is closely constrained by available data. I end with a speculation regarding the value of having theories that are maximally formal, even mathematical.     

The Insufficiency of the Dutch Book Argument

It is a common view that the axioms of probability can be derived from the following assumptions: (a) probabilities reflect (rational) degrees of belief, (b) degrees of belief can be measured as betting quotients; and (c) a rational agent must select betting quotients that are coherent. In this paper, I argue that a consideration of reasonable betting behaviour, with respect to the alleged derivation of the first axiom of probability, suggests that (b) and (c) are incorrect. In particular, I show how a rational agent might assign a ‘probability’ of zero to an event which she is sure will occur.     

How to build a brain: from function to implementation

To have a fully integrated understanding of neurobiological systems, we must address two fundamental questions: 1. What do brains do (what is their function)? and 2. How do brains do whatever it is that they do (how is that function implemented)? I begin by arguing that these questions are necessarily inter-related. Thus, addressing one without consideration of an answer to the other, as is often done, is a mistake. I then describe what I take to be the best available approach to addressing both questions. Specifically, to address 2, I adopt the Neural Engineering Framework (NEF) of Eliasmith &; Anderson [Neural engineering: Computation representation and dynamics in neurobiological systems. Cambridge, MA: MIT Press, 2003] which identifies implementational principles for neural models. To address 1, I suggest that adopting statistical modeling methods for perception and action will be functionally sufficient for capturing biological behavior. I show how these two answers will be mutually constraining, since the process of model selection for the statistical method in this approach can be informed by known anatomical and physiological properties of the brain, captured by the NEF. Similarly, the application of the NEF must be informed by functional hypotheses, captured by the statistical modeling approach.     

Expectations about the long-term consequences of recurring defensive interpersonal behavior

We investigated individuals’ expectations about the long-term impact of recurring defensive behavior on relationships. Specifically, we presented interpersonal vignettes to 96 participants who described their expectations about how the relationships would turn out. Consistent with predictions based on the theory of interpersonal defense (Westerman, 1998, 2005; Westerman & Prieto, 2006; Westerman & Steen, in press), as a group, participants anticipated that, over the long term, defensive behavior would (a) avert clear-cut instances of feared outcomes, (b) thwart the realization of wished-for outcomes, (c) promote positive outcomes related to, but distinct from wished-for outcomes, and (d) promote negative outcomes related to, but distinct from feared consequences (in a form of self-fulfilling prophesy). In support of a hypothesis regarding individual differences, self-reports of defensiveness were associated with less appreciation for the long-term costs of interpersonal defense. In the discussion, we consider alternative models for explaining this relationship between defensiveness and individuals’ expectations downplaying costs.     

Speech-associated gestures, Broca’s area, and the human mirror system

Speech-associated gestures are hand and arm movements that not only convey semantic information to listeners but are themselves actions. Broca’s area has been assumed to play an important role both in semantic retrieval or selection (as part of a language comprehension system) and in action recognition (as part of a “mirror” or “observation–execution matching” system). We asked whether the role that Broca’s area plays in processing speech-associated gestures is consistent with the semantic retrieval/selection account (predicting relatively weak interactions between Broca’s area and other cortical areas because the meaningful information that speech-associated gestures convey reduces semantic ambiguity and thus reduces the need for semantic retrieval/selection) or the action recognition account (predicting strong interactions between Broca’s area and other cortical areas because speech-associated gestures are goal-direct actions that are “mirrored”). We compared the functional connectivity of Broca’s area with other cortical areas when participants listened to stories while watching meaningful speech-associated gestures, speech-irrelevant self-grooming hand movements, or no hand movements. A network analysis of neuroimaging data showed that interactions involving Broca’s area and other cortical areas were weakest when spoken language was accompanied by meaningful speech-associated gestures, and strongest when spoken language was accompanied by self-grooming hand movements or by no hand movements at all. Results are discussed with respect to the role that the human mirror system plays in processing speech-associated movements.     

Responsibility and obsessive-compulsive disorder: an experimental test

To test the causal status of responsibility in obsessive-compulsive disorder (OCD), an experiment was executed in which responsibility was experimentally manipulated. OCD patients, non-OCD anxiety controls, and non-patients executed a classification task in either a high or a low responsibility (LoRes) condition. Subjective ratings related to danger and responsibility indicated that the manipulation was successful. Subjective OCD-like experiences and checking behaviors were higher in OCD patients in the high responsibility (HiRes) condition than in all other groups. Although the checking subscale of the Padua Inventory correlated with subjective ratings in the OCD patients in the HiRes condition, it was not associated with checking behaviors. The results confirm the hypothesis that responsibility plays a causal role in OCD.     

From mere coincidences to meaningful discoveries

People's reactions to coincidences are often cited as an illustration of the irrationality of human reasoning about chance. We argue that coincidences may be better understood in terms of rational statistical inference, based on their functional role in processes of causal discovery and theory revision. We present a formal definition of coincidences in the context of a Bayesian framework for causal induction: a coincidence is an event that provides support for an alternative to a currently favored causal theory, but not necessarily enough support to accept that alternative in light of its low prior probability. We test the qualitative and quantitative predictions of this account through a series of experiments that examine the transition from coincidence to evidence, the correspondence between the strength of coincidences and the statistical support for causal structure, and the relationship between causes and coincidences. Our results indicate that people can accurately assess the strength of coincidences, suggesting that irrational conclusions drawn from coincidences are the consequence of overestimation of the plausibility of novel causal forces. We discuss the implications of our account for understanding the role of coincidences in theory change.     

Rapid learning of syllable classes from a perceptually continuous speech stream

To learn a language, speakers must learn its words and rules from fluent speech; in particular, they must learn dependencies among linguistic classes. We show that when familiarized with a short artificial, subliminally bracketed stream, participants can learn relations about the structure of its words, which specify the classes of syllables occurring in first and last word positions. By studying the effect of familiarization length, we compared the general predictions of associative theories of learning and those of models postulating separate mechanisms for quickly extracting the word structure and for tracking the syllable distribution in the stream. As predicted by the dual-mechanism model, the preference for structurally correct items was negatively correlated with the familiarization length. This result is difficult to explain by purely associative schemes; an extensive set of neural network simulations confirmed this difficulty. Still, we show that powerful statistical computations operating on the stream are available to our participants, as they are sensitive to co-occurrence statistics among non-adjacent syllables. We suggest that different learning mechanisms analyze speech on-line: A rapid mechanism extracting structural information about the stream, and a slower mechanism detecting statistical regularities among the items occurring in it.