Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA304

Poster Communications

Does Colour alter performance on Letter Cancellation tasks?

A. Dixit1, P. H. Kamble1, A. Singhal1, K. Datta1, M. Gadhvi1

1. Physiology, AIIMS Jodhpur, Jodhpur, Rajasthan, India.


Cognitive function broadly refers to various domains, including memory, language, executive function, processing speed and visuospatial ability. Letter Cancellation Tasks (LCT), a group of cognitive performance tasks are reliable measures of concentration, visual scanning and executive function and useful test for assessment of dementia. Colour is a modality that affects attention, perception and response activation. Ability to discriminate colour has been reported to be altered in Alzheimer's Disease (1). Thus, we hypothesize that addition of colour in LCT could help in detection of cognitive changes in disease like Alzheimer's. As a prelude to the above hypothesis the present study was done to evaluate the effect of colour on performance of LCT in normal individuals. Materials and Methods: The present study was conducted after approval of Institutional Ethics Committee. 22 healthy male subjects in the age group of 18-40 years were recruited for the study after taking written-informed consent. The subjects with history of visual defects like colour blindness, neuropsychological illness, stroke, or serious mental illness such as depression or schizophrenia; history of drug intake like alcohol, cocaine, heroin etc. and less than 5 years of schooling in English were excluded from the study. Subjects were asked to cancel out letters in four different colours i.e. Black, Blue, Green and Red versions of letter cancellation tasks in English language administered randomly. Letter cancellation involved One, Two and Three Letter cancellations. Each LCT consisted of 960 letters with 25% as target letters. The font size and RGB values of the letters were kept same in all versions. The total time taken to complete each test was noted and analysed statistically using SPSS by repeated measures ANOVA. The level of significance was kept at 0.05. Results The results are summarised in Table 1: The time taken to complete LCT showed significant difference (p < 0.001) in the four colours (Black, Red, Green and Blue) for each group with the time for Blue being the shortest and for Black being the longest. There was significant difference between the time to complete between the three groups i.e. One LCT, Two LCT and Three LCT for each colour, with the time for Three LCT being the maximum and One LCT being the minimum. Conclusions/Implications: The present study demonstrated that colour effected the performance on Letter Cancellations Tasks. The changes in time taken reflect the time for processing of signal by the brain which could be at the level of cones or various levels in the visual pathway including the cortex. Disease processes that effect colour processing could thus effect performance on cognitive tests that involve use of different colours.

Where applicable, experiments conform with Society ethical requirements