title: Do the letters F, A and S represent Indonesian letter fluency stimuli?
abstract: BACKGROUND
  The letters F, A and S, originally used in the English letter fluency stimuli test, have been frequently adopted to assess executive function in many languages. However, few studies reported the significance of FAS testing employed in different languages. The current study explored whether FAS could be widely applied to the Indonesian language.
  
  
  METHODS
  A total of 211 undergraduate students from state and private universities who participated in this study were randomly assigned into four groups. Each group was exposed to six different letter fluency stimuli. The total number of words the participants produced for each letter stimulus were averaged and ranked to determine the degree of difficulty in generating words. Furthermore, the normal distribution and equal ratio comparison were examined to verify the representative letter fluency stimuli. In addition, the effect of sex and university affiliation on letter fluency performance was also analyzed.
  
  
  RESULTS
  The letters A and S were among the easiest letters used to generate words; however, the letter F was regarded as a difficult stimulus. Furthermore, only the number of words beginning the letter S was distributed according to a normal curve. The number of words starting with the letters F and A were not normally distributed. Although sex difference was not associated with letter fluency performance, difference in university affiliation showed a significant effect on performance.
  
  
  CONCLUSIONS
  Our findings suggest that consideration of several stimuli factors is required to accurately measure performance in the letter fluency task in a specific language.
authors.affiliation: Faculty of Psychology, University of Indonesia, Depok City, Indonesia; Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan.
authors.forename: Donny
authors.initials: D
authors.lastname: Hendrawan
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hatta
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohira
mesh_terms: D005260:Female; D006801:Humans; D007214:Indonesia; D007802:Language; D008297:Male; D009483:Neuropsychological Tests
keywords: Kolmogorov-Smirnov test of normality; cultural background difference; letter fluency; ranking of letters; ratio comparison