In this study, a new trial analysis was conducted by using conventional experiment data, which were obtained when varying the office environment and work motivation. The answering time data was collected while conducting cognitive task which abstracted office work, and it was fitted to the sum of two log-normal distributions, that was different from the conventional analysis fitted to only one log-normal distribution. Using parameters got from the fitting analysis as indices, it is expected that the characteristics of answering time data of cognitive task, which is considered to have relationship between the intellectual concentration, can be discussed in detail and this method is expected to bring a new aspect of discussion about intellectual concentration.