The present research examines the nature of the different processes that have been proposed to un... more The present research examines the nature of the different processes that have been proposed to underlie semantic priming. Specifically, it has been argued that priming arises as a result of automatic target activation and/or the use of strategies like prospective expectancy generation and retrospective semantic matching. This article investigates the extent that these processes rely on cognitive resources by experimentally manipulating working memory load. To disentangle prospective and retrospective processes , prime–target pairs were selected such that they were symmetrically associated (e.g., answer-question; SYM) or asymmetrically associated in either the forward direction (e.g., panda-bear; FA) or the backward direction (e.g., ball-catch; BA). The results showed that priming for FA pairs completely evaporated under a high working memory load but that it remained stable for BA and SYM pairs. This was taken to mean that prospective processes, which are assumed to cause FA priming, require cognitive resources, whereas retrospective processes, which lead to BA priming, are relatively effortless.
In the past decade, several studies have used scaling and clustering techniques to document seman... more In the past decade, several studies have used scaling and clustering techniques to document semantic storage deficits in patients with Alzheimer's disease and in schizophrenia. In this article the authors argued that many of the conclusions drawn from these studies are unjustified by the data. They reviewed the methodology used in these studies and presented data from simulation studies to further investigate the validity of their conclusions. The authors elaborate on the criteria needed to exclude alternative accounts of the data and present empirical data from patients with Alzheimer's disease and normal control participants to demonstrate that analyses of the patients' proximity data do not provide unambiguous evidence for a generalized semantic storage deficit.
We previously reported the neuropsychological consequences of a lesion confined to the middle and... more We previously reported the neuropsychological consequences of a lesion confined to the middle and posterior part of the right fusiform gyrus (case JA) causing a partial loss of knowledge of visual attributes of concrete entities in the absence of category-selectivity (animate versus inanimate). We interpreted this in the context of a two-step model that distinguishes structural description knowledge from associative-semantic processing and implicated the lesioned area in the former process. To test this hypothesis in the intact brain, multi-voxel pattern analysis was used in a series of event-related fMRI studies in a total of 46 healthy subjects. We predicted that activity patterns in this region would be determined by the identity of rather than the conceptual similarity between concrete entities. In a prior behavioral experiment features were generated for each entity by more than 1000 subjects. Based on a hierarchical clustering analysis the entities were organised into 3 semantic clusters (musical instruments, vehicles, tools). Entities were presented as words or pictures. With foveal presentation of pictures, cosine similarity between fMRI response patterns in right fusiform cortex appeared to reflect both the identity of and the semantic similarity between the entities. No such effects were found for words in this region. The effect of object identity was invariant for location, scaling, orientation axis and color (grayscale versus color). It also persisted for different exemplars referring to a same concrete entity. The apparent semantic similarity effect however was not invariant. This study provides further support for a neurobiological distinction between structural description knowledge and processing of semantic relationships and confirms the role of right mid-posterior fusiform cortex in the former process, in accordance with previous lesion evidence.
The present research examines the nature of the different processes that have been proposed to un... more The present research examines the nature of the different processes that have been proposed to underlie semantic priming. Specifically, it has been argued that priming arises as a result of automatic target activation and/or the use of strategies like prospective expectancy generation and retrospective semantic matching. This article investigates the extent that these processes rely on cognitive resources by experimentally manipulating working memory load. To disentangle prospective and retrospective processes , prime–target pairs were selected such that they were symmetrically associated (e.g., answer-question; SYM) or asymmetrically associated in either the forward direction (e.g., panda-bear; FA) or the backward direction (e.g., ball-catch; BA). The results showed that priming for FA pairs completely evaporated under a high working memory load but that it remained stable for BA and SYM pairs. This was taken to mean that prospective processes, which are assumed to cause FA priming, require cognitive resources, whereas retrospective processes, which lead to BA priming, are relatively effortless.
In the past decade, several studies have used scaling and clustering techniques to document seman... more In the past decade, several studies have used scaling and clustering techniques to document semantic storage deficits in patients with Alzheimer's disease and in schizophrenia. In this article the authors argued that many of the conclusions drawn from these studies are unjustified by the data. They reviewed the methodology used in these studies and presented data from simulation studies to further investigate the validity of their conclusions. The authors elaborate on the criteria needed to exclude alternative accounts of the data and present empirical data from patients with Alzheimer's disease and normal control participants to demonstrate that analyses of the patients' proximity data do not provide unambiguous evidence for a generalized semantic storage deficit.
We previously reported the neuropsychological consequences of a lesion confined to the middle and... more We previously reported the neuropsychological consequences of a lesion confined to the middle and posterior part of the right fusiform gyrus (case JA) causing a partial loss of knowledge of visual attributes of concrete entities in the absence of category-selectivity (animate versus inanimate). We interpreted this in the context of a two-step model that distinguishes structural description knowledge from associative-semantic processing and implicated the lesioned area in the former process. To test this hypothesis in the intact brain, multi-voxel pattern analysis was used in a series of event-related fMRI studies in a total of 46 healthy subjects. We predicted that activity patterns in this region would be determined by the identity of rather than the conceptual similarity between concrete entities. In a prior behavioral experiment features were generated for each entity by more than 1000 subjects. Based on a hierarchical clustering analysis the entities were organised into 3 semantic clusters (musical instruments, vehicles, tools). Entities were presented as words or pictures. With foveal presentation of pictures, cosine similarity between fMRI response patterns in right fusiform cortex appeared to reflect both the identity of and the semantic similarity between the entities. No such effects were found for words in this region. The effect of object identity was invariant for location, scaling, orientation axis and color (grayscale versus color). It also persisted for different exemplars referring to a same concrete entity. The apparent semantic similarity effect however was not invariant. This study provides further support for a neurobiological distinction between structural description knowledge and processing of semantic relationships and confirms the role of right mid-posterior fusiform cortex in the former process, in accordance with previous lesion evidence.
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Papers by G Storms