Time to imagine space: A chronometric exploration of imaginal neglect. Bartolomeo, P., Bachoud-Lévi, A., Chokron, S., & Azouvi, P. In 22nd European Workshop on Cognitive Neuropsychology, Bressanone, Italy, 2004.
abstract   bibtex   
Background. When describing known places from memory, patients with left spatial neglect can mention more right- than left-sided details, thus suggesting that they cannot build or explore left locations in visual mental imagery. However, tasks based on place description have several shortcomings; (1) there is no guarantee that patients are really employing visual mental imagery abilities: verbal-propositional knowledge could for example be used to report a list of geographical details; (2) idiosyncratic responses are possible, depending, e.g., on the participant’s residency or vacation places; (3) performance may be strongly dependent upon the pre-morbid cultural level (4) the number of details given is often insufficient to permit statistical analysis; (4) there is no way of knowing where participants put the centre of their mental images, and consequently which items are left and which are right of the imagined centre. These problems may result in low sensibility and specificity of place descriptions in the diagnosis of imaginal neglect. We present a new test which strongly encourages participants to use visual mental imagery. The relevant items (French geographical details) are given to the participant, and do not depend on his/her memory recall. The centre from which to start the mental exploration is provided at the beginning of each trial, by asking participants to imagine the location of Paris in a map of France. Finally, the analysis of accuracy and response times (RTs) allows a quantitative estimation of imaginal neglect. Methods. Participants are invited to build a visual mental image of the map of France and hear the computerized presentation of the word “Paris”, followed by one of the names of 40 geographical locations (towns or regions), 20 left (e.g., “Bordeaux”) and 20 right (e.g., “Alsace”) of a meridian line passing through Paris. Participants press a left- or a right-sided key depending on the imagined position (left or right) of the target. Accuracy and response times (RTs) from input presentation to response production are recorded. In a further task, designed to control for a possible response bias, patients hear the word “left” or “right”, and respond by pressing the corresponding key. Results. Twelve normal individuals had symmetrical performance on the description of the map of France (left, 9.58 ± 3.96 details; right, 9.75 ± 4.71 details), the geographical RT task (accuracy, 93% correct for both imagined sides; RTs, left, 703 ± 248 ms; right, 712 ± 153 ms), and the response bias RT task (left, 639 ± 98 ms; right, 557 ± 160 ms). Twenty patients with unilateral right hemisphere lesions, of whom 8 showed signs of visual neglect on paper-and-pencil tests, were also tested. On the map description, performance was as follows: neglect patients, left, 8.13 ± 4.73 details; right, 6.63 ± 3.89 details; patients without neglect, left, 7.45 ± 6.01; right, 9.27 ± 5.81. On single-case analysis, only one patient, showing no sign of visual neglect, had asymmetrical performance (4 left vs. 12 right details; binomial test, p=0.03). On the imaginal RT task, one neglect patient always pressed the right-sided key and was excluded from further analysis. None of the remaining patients showed any significant bias in accuracy of response (left, mean 72% correct; right, mean 73% correct). RTs were entered in a repeated-measures analysis of variance with group (neglect, non-neglect, controls) as between factor and side (left, right) and task (geographical RT, response bias RT) as within factors. There was a significant interaction between group, side and task, F(2, 28)=5.36, p=0.01, because the neglect group had slower left than right RTs on both tasks, but the asymmetry was greater for the geographical RT task (left, 2088 ms; right, 1557 ms) than for the response bias task (left, 1103 ms; right, 922 ms). On single-case analysis using the response bias task as a baseline, two neglect patients were identified whose L-R asymmetry on the geographical task was greater (99% confidence intervals) than that predicted by the response bias. For these two patients, the evidence from place description was insufficient to demonstrate imaginal neglect. They had overall good accuracy on the geographical RT task, which suggests that left-sided details were not lost from their mental map of space, but only “explored” less efficiently. Conclusions. We describe a new RT test whose results can demonstrate and quantify imaginal neglect in right brain-damaged patients. Our geographical RT test does not suffer from problems affecting place description tasks, can be used to test hypotheses about imaginal neglect and its relationships with visual neglect, and can be repeated to assess patients’ performance before and after rehabilitation.
@inproceedings{bartolomeo_time_2004,
	address = {Bressanone, Italy},
	title = {Time to imagine space: {A} chronometric exploration of imaginal neglect},
	abstract = {Background. When describing known places from memory, patients with left spatial neglect can mention more right- than left-sided details, thus suggesting that they cannot build or explore left locations in visual mental imagery. However, tasks based on place description have several shortcomings; (1) there is no guarantee that patients are really employing visual mental imagery abilities: verbal-propositional knowledge could for example be used to report a list of geographical details; (2) idiosyncratic responses are possible, depending, e.g., on the participant’s residency or vacation places; (3) performance may be strongly dependent upon the pre-morbid cultural level (4) the number of details given is often insufficient to permit statistical analysis; (4) there is no way of knowing where participants put the centre of their mental images, and consequently which items are left and which are right of the imagined centre. These problems may result in low sensibility and specificity of place descriptions in the diagnosis of imaginal neglect. We present a new test which strongly encourages participants to use visual mental imagery. The relevant items (French geographical details) are given to the participant, and do not depend on his/her memory recall. The centre from which to start the mental exploration is provided at the beginning of each trial, by asking participants to imagine the location of Paris in a map of France. Finally, the analysis of accuracy and response times (RTs) allows a quantitative estimation of imaginal neglect. Methods. Participants are invited to build a visual mental image of the map of France and hear the computerized presentation of the word “Paris”, followed by one of the names of 40 geographical locations (towns or regions), 20 left (e.g., “Bordeaux”) and 20 right (e.g., “Alsace”) of a meridian line passing through Paris. Participants press a left- or a right-sided key depending on the imagined position (left or right) of the target. Accuracy and response times (RTs) from input presentation to response production are recorded. In a further task, designed to control for a possible response bias, patients hear the word “left” or “right”, and respond by pressing the corresponding key. Results. Twelve normal individuals had symmetrical performance on the description of the map of France (left, 9.58 ± 3.96 details; right, 9.75 ± 4.71 details), the geographical RT task (accuracy, 93\% correct for both imagined sides; RTs, left, 703 ± 248 ms; right, 712 ± 153 ms), and the response bias RT task (left, 639 ± 98 ms; right, 557 ± 160 ms). Twenty patients with unilateral right hemisphere lesions, of whom 8 showed signs of visual neglect on paper-and-pencil tests, were also tested. On the map description, performance was as follows: neglect patients, left, 8.13 ± 4.73 details; right, 6.63 ± 3.89 details; patients without neglect, left, 7.45 ± 6.01; right, 9.27 ± 5.81. On single-case analysis, only one patient, showing no sign of visual neglect, had asymmetrical performance (4 left vs. 12 right details; binomial test, p=0.03). On the imaginal RT task, one neglect patient always pressed the right-sided key and was excluded from further analysis. None of the remaining patients showed any significant bias in accuracy of response (left, mean 72\% correct; right, mean 73\% correct). RTs were entered in a repeated-measures analysis of variance with group (neglect, non-neglect, controls) as between factor and side (left, right) and task (geographical RT, response bias RT) as within factors. There was a significant interaction between group, side and task, F(2, 28)=5.36, p=0.01, because the neglect group had slower left than right RTs on both tasks, but the asymmetry was greater for the geographical RT task (left, 2088 ms; right, 1557 ms) than for the response bias task (left, 1103 ms; right, 922 ms). On single-case analysis using the response bias task as a baseline, two neglect patients were identified whose L-R asymmetry on the geographical task was greater (99\% confidence intervals) than that predicted by the response bias. For these two patients, the evidence from place description was insufficient to demonstrate imaginal neglect. They had overall good accuracy on the geographical RT task, which suggests that left-sided details were not lost from their mental map of space, but only “explored” less efficiently. Conclusions. We describe a new RT test whose results can demonstrate and quantify imaginal neglect in right brain-damaged patients. Our geographical RT test does not suffer from problems affecting place description tasks, can be used to test hypotheses about imaginal neglect and its relationships with visual neglect, and can be repeated to assess patients’ performance before and after rehabilitation.},
	booktitle = {22nd {European} {Workshop} on {Cognitive} {Neuropsychology}},
	author = {Bartolomeo, P. and Bachoud-Lévi, A.C. and Chokron, S. and Azouvi, P.},
	year = {2004},
	keywords = {\#nosource, ⛔ No DOI found},
}

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