Image Modules Work Wordlessly
University students saw pictures of five simple objects and words corresponding to their names. Participants were instructed to keep a silent mental count of the appearance of a specific target. For instance, in the first study, they looked for the word "globe." Its appearance on screen created a noticeable brain response. "We found that the appearance of the word 'globe' elicited a large electrical response called the P300, a positive-going ERP that occurs about 300-500 ms after the presentation of a target, " author Todd Watson states. Psychophysiology (recent issue)
---
This is a standard response to a search target. More interesting: a picture of the globe got a similar, weaker response. In a second study, the picture of the globe was the target. As expected, that target got a strong response. But here, the word “globe” did not get a strong response.
This is a story of set, search, and closure. I think we could view the P300 as a physiological analogue of closure. Momentary closure: “I found one.” This is, after all, the Easter egg version of search. The set is asymmetric here. A set to look for a word activates both the module that represents the word and the module that represents the concrete denotation of the word. A set to look for the concrete denotation does not necessarily activate the word module.
Part of the asymmetry may come from the issue of meaning. If you see the word “globe,” you are sure that you know what it means. To draw that conclusion, you would need to look it up in your repertoire of concrete representations. If you see words like “wabe,” or “drog,” you are sure that you do not know the meanings because your search gets no returns.
It would be interesting to see the same experiment done with nonsense words. It would also be interesting to see the same experiment done with a real globe as well as an image of a globe.
This is an important paradigm in that it provides an efficient way to investigate connections among modules with equipment more readily available than fMRI.
---
This is a standard response to a search target. More interesting: a picture of the globe got a similar, weaker response. In a second study, the picture of the globe was the target. As expected, that target got a strong response. But here, the word “globe” did not get a strong response.
This is a story of set, search, and closure. I think we could view the P300 as a physiological analogue of closure. Momentary closure: “I found one.” This is, after all, the Easter egg version of search. The set is asymmetric here. A set to look for a word activates both the module that represents the word and the module that represents the concrete denotation of the word. A set to look for the concrete denotation does not necessarily activate the word module.
Part of the asymmetry may come from the issue of meaning. If you see the word “globe,” you are sure that you know what it means. To draw that conclusion, you would need to look it up in your repertoire of concrete representations. If you see words like “wabe,” or “drog,” you are sure that you do not know the meanings because your search gets no returns.
It would be interesting to see the same experiment done with nonsense words. It would also be interesting to see the same experiment done with a real globe as well as an image of a globe.
This is an important paradigm in that it provides an efficient way to investigate connections among modules with equipment more readily available than fMRI.
posted by Selby Evans at 8:28 AM
0 Comments:
Post a Comment
<< Home