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Is there evidence for amodality of mental representation in categorization tasks of words and pictures?
Neurolmage
11, Number
5, 2000,
Part 2 of 2 Parts 10
E bl”
MEMORY
- LEARNING
Is there evidence for amodality of mental representation in categorization tasks of words and pictures? Werner Krause*, Barbara Schackt, Ursula Krause*, Nicole Kotkamp*, Heiko Tie&e*, Eva Moeller? *Institute of Psychology, Chair of General Psychology, Jena, Germany tlnstitute of Medical Statistics, Computer Science and Documentation, Jena, Germany Objectives: Categorization representation Experiment
processes by means
(Grabowski et al. 1997) of words and pictures of instantaneous EEG coherence.
are investigated
in order to identify
the modality
of mental
and methods:
Three well trained subjects carried out two different tasks: categorization and pattern comparison. Two kinds of stimuli were given in blocks: words and pictures. The two words or two pictures were presented with an interstimulus interval on a computer screen. For pattern comparison the subject has to decide about the identity of the two words or pictures. In case of categorization the subjects have to classify the two words or pictures. Thereby a category concept must be activated in contrast to pattern comparison. The EEG was recorded from 19 scalp electrodes (10 /20 system, ear lob reference. 256 Hz). Only artifact-free trials with correct positive answers were included in further analysis. Instantaneous coherence analysis (see e.g. Schack et al. 1999) was performed 082 for 39 electrode pairs. The frequency band 13-20 Hz allowed the best discrimination between categorization and pattern comparison. Therefore, the time courses of coherence with regard to this frequency band were analyzed. Maximal coherence values were calculated for each trial and each electrode pair within the time interval from the presentation of the second item up to the end of the task. On the basis of calculating the correlation between the coherence vectors of all pairs of time points within the same time interval the single trials were subdivided into segments with stable coherence values. The segments were clustered into six classes. The time points of beginning, the duration and the mean coherence values of the segments of each cluster were calculated. Results: -Subjects need the same reaction time for classifying words and pictures. -The values of maximal coherence for the electrode pairs T3/C3. C3/Cz, T3/T5. C3/P3, F3/Pz are significantly higher for categorization than for pattern comparison both for word and for picture representation. At the same time they are not different with regard to the kind of stimulus both for categorization and for pattern comparison. -The distribution of segments of the cluster with high coherence values within the left hemisphere differs extremely with regard to the modality both for presentation of words and pictures (see Fig. 1). -The distribution of segments of the cluster with high coherence values within the left hemisphere does not differ with regard to the kind of stimulus. Fig.2 shows the result for categorization. Conclusion: The same distribution of segments with activation in the left hemisphere during categorir.ation of given words and pictures and the increased maximal coherence values for identical cortical areas in the left hemisphere during categorization of- given words and picture\ I-epresentation in both modalities. Tberr is no c\ idence for the amodality ot mental representation (Engelkamp 1990, Krause et al.1998, 1999). References: I. 2. 3. 4. 5.
Schack. B., Krause, W., Krause, W., Grabowski, Engelkamp,
* Sponsored
GriesAbach. G.. Krause, W., Int. J. Psychophysiol., 1999, 31: 219-240 Gibbons. H., &hack. B.. Neuro Report, 1998, 9: 1649-1653. Kotkamp, N.. Tietze, H., MGller, E., Schack, B., NeuroImage. 1999, 9,6. S1083 T.J.. Damasio, H.. Dam&o, A.R., NeuroImage. 1997, 5.4,562 J.( 1990) Das menschliche Gedkhtnis. Hogrefe, Gettingen, Toronto. Zurich
by DFG
(Kr
1333/3-I,
Scha 741/l-2).
s410
\prak for a conceptual in categorization task\
11, Number
5, 2000,
Part 2 of 2 Parts 10
E bl”
MEMORY
- LEARNING
Is there evidence for amodality of mental representation in categorization tasks of words and pictures? Werner Krause*, Barbara Schackt, Ursula Krause*, Nicole Kotkamp*, Heiko Tie&e*, Eva Moeller? *Institute of Psychology, Chair of General Psychology, Jena, Germany tlnstitute of Medical Statistics, Computer Science and Documentation, Jena, Germany Objectives: Categorization representation Experiment
processes by means
(Grabowski et al. 1997) of words and pictures of instantaneous EEG coherence.
are investigated
in order to identify
the modality
of mental
and methods:
Three well trained subjects carried out two different tasks: categorization and pattern comparison. Two kinds of stimuli were given in blocks: words and pictures. The two words or two pictures were presented with an interstimulus interval on a computer screen. For pattern comparison the subject has to decide about the identity of the two words or pictures. In case of categorization the subjects have to classify the two words or pictures. Thereby a category concept must be activated in contrast to pattern comparison. The EEG was recorded from 19 scalp electrodes (10 /20 system, ear lob reference. 256 Hz). Only artifact-free trials with correct positive answers were included in further analysis. Instantaneous coherence analysis (see e.g. Schack et al. 1999) was performed 082 for 39 electrode pairs. The frequency band 13-20 Hz allowed the best discrimination between categorization and pattern comparison. Therefore, the time courses of coherence with regard to this frequency band were analyzed. Maximal coherence values were calculated for each trial and each electrode pair within the time interval from the presentation of the second item up to the end of the task. On the basis of calculating the correlation between the coherence vectors of all pairs of time points within the same time interval the single trials were subdivided into segments with stable coherence values. The segments were clustered into six classes. The time points of beginning, the duration and the mean coherence values of the segments of each cluster were calculated. Results: -Subjects need the same reaction time for classifying words and pictures. -The values of maximal coherence for the electrode pairs T3/C3. C3/Cz, T3/T5. C3/P3, F3/Pz are significantly higher for categorization than for pattern comparison both for word and for picture representation. At the same time they are not different with regard to the kind of stimulus both for categorization and for pattern comparison. -The distribution of segments of the cluster with high coherence values within the left hemisphere differs extremely with regard to the modality both for presentation of words and pictures (see Fig. 1). -The distribution of segments of the cluster with high coherence values within the left hemisphere does not differ with regard to the kind of stimulus. Fig.2 shows the result for categorization. Conclusion: The same distribution of segments with activation in the left hemisphere during categorir.ation of given words and pictures and the increased maximal coherence values for identical cortical areas in the left hemisphere during categorization of- given words and picture\ I-epresentation in both modalities. Tberr is no c\ idence for the amodality ot mental representation (Engelkamp 1990, Krause et al.1998, 1999). References: I. 2. 3. 4. 5.
Schack. B., Krause, W., Krause, W., Grabowski, Engelkamp,
* Sponsored
GriesAbach. G.. Krause, W., Int. J. Psychophysiol., 1999, 31: 219-240 Gibbons. H., &hack. B.. Neuro Report, 1998, 9: 1649-1653. Kotkamp, N.. Tietze, H., MGller, E., Schack, B., NeuroImage. 1999, 9,6. S1083 T.J.. Damasio, H.. Dam&o, A.R., NeuroImage. 1997, 5.4,562 J.( 1990) Das menschliche Gedkhtnis. Hogrefe, Gettingen, Toronto. Zurich
by DFG
(Kr
1333/3-I,
Scha 741/l-2).
s410
\prak for a conceptual in categorization task\