Putting concepts into context

Published online: 9 June 2016At first glance, conceptual representations (e.g., our internal notion of the object Blemon^) seem static; we have the impression that there is something that the concept lemon Bmeans^ (a sour, yellow, football-shaped citrus fruit) and that this meaning does not vary. Research in semantic memory has traditionally taken this Bstatic^ perspective. Consequently, only effects demonstrated across a variety of contexts have typically been considered informative regarding the architecture of the semantic system. In this review, we take the opposite approach: We review instances of context-dependent conceptual activation at many different timescales—from long-term experience, to recent experience, to the current task goals, to the unfolding process of conceptual activation itself—and suggest that the pervasive effects of context across all of these timescales indicate that rather than being static, conceptual representations are constantly changing and are inextricably linked to their contexts

Noticing causal properties of objects from sequence statistics

How do we learn non-physical properties of physical objects? We explored how the statistical structure of eventscan be a source of object property learning. Twenty-five participants saw sequences of visual events surrounding two distinctobjects. Object identity determined 1) the direction of a high transition probability between two events, and 2) the frequency oftwo other events. Learning was unsupervised and unguided. However, participants spontaneously noticed these regularities. Inan explicit, verbal judgment task, they discriminated between frequent vs. rare events (t(24) = 10.7, p< 0.00001) and betweenpredictive vs. non-predictive event pairs (t(24) = 3.04, p<0.01), as appropriate to the object. These statistics gave rise to distinctconceptual interpretations: participants ascribed a causal interpretation to the predictive statistics (t(24) = 1.91, p<0.05) morethan to events frequently co-occurring with the objects (t(24) = 3.00, p<0.01). Such learning may underlie concept acquisition,particularly of functional kinds like artifacts

Functional Neuroimaging Can Support Causal Claims about Brain Function

Cognitive neuroscientists habitually deny that functional neuroimaging can furnish causal information about the relationship between brain events and behavior. However, imaging studies do provide causal information about those relationships although not causal certainty. Although popular portrayals of functional neuroimaging tend to attribute too much inferential power to the technique, we should restrain ourselves from ascribing it too little

Perceptual and conceptual sources of priming on a word generation task

Repetition of any number of cognitive processes can facilitate subsequent performance (i.e., repetition priming). In this study, we explored several candidate mechanisms that could account for repetition priming on a word generation task. In Experiment 1, we examined whether repetition of semantic processing is necessary for priming on this task. In Experiment 2, we examined whether repetition of semantic processing is sufficient for priming on this task. In both experiments, we additionally examined the effect of changing the specific nature of the semantic retrieval task (i.e., from visual to functional, and vice versa) on performance. The results from these experiments indicated that repetition of semantic processing is both necessary and sufficient to produce a facilitation effect on the word generation task. However, semantic processing of the same attribute does not need to be repeated for facilitation effects to occur. Implications of these findings for theories of the representation and retrieval of semantic knowledge are discussed

Prefrontal Cortical Response to Conflict during Semantic and Phonological Tasks

Debates about the function of the prefrontal cortex are as old as the field of neuropsychology—often dated to Paul Broca’s seminal work. Theories of the functional organization of the prefrontal cortex can be roughly divided into those that describe organization by process and those that describe organization by material. Recent studies of the function of the posterior, left inferior frontal gyrus (pLIFG) have yielded two quite different interpretations: One hypothesis holds that the pLIFG plays a domain-specific role in phonological processing, whereas another hypothesis describes a more general function of the pLIFG in cognitive control. In the current study, we distinguish effects of increasing cognitive control demands from effects of phonological processing. The results support the hypothesized role for the pLIFG in cognitive control, and more task-specific roles for posterior areas in phonology and semantics. Thus, these results suggest an alternative explanation of previously reported phonology-specific effects in the pLIFG

A Matched Filter Hypothesis for Cognitive Control

The prefrontal cortex exerts top-down influences on several aspects of higher-order cognition by functioning as a filtering mechanism that biases bottom-up sensory information toward a response that is optimal in context. However, research also indicates that not all aspects of complex cognition benefit from prefrontal regulation. Here we review and synthesize this research with an emphasis on the domains of learning and creative cognition, and outline how the appropriate level of cognitive control in a given situation can vary depending on the organism's goals and the characteristics of the given task. We offer a Matched Filter Hypothesis for cognitive control, which proposes that the optimal level of cognitive control is task-dependent, with high levels of cognitive control best suited to tasks that are explicit, rule-based, verbal or abstract, and can be accomplished given the capacity limits of working memory and with low levels of cognitive control best suited to tasks that are implicit, reward-based, non-verbal or intuitive, and which can be accomplished irrespective of working memory limitations. Our approach promotes a view of cognitive control as a tool adapted to a subset of common challenges, rather than an all-purpose optimization system suited to every problem the organism might encounter

The Effects of Anodal Stimulation of the Left Prefrontal Cortex on Sentence Production

Most studies in which Anodal Transcranial Direct Current Stimulation (A-tDCS) has been used to improve language production have focused on single words. Yet sentence production requires more than lexical retrieval. For example, successful suppression of the past and careful planning of the future are two critical requirements for producing a correct sentence. Can A-tDCS improves those, and by extension, production at the sentence level