In Chapter 2, I presented data on the speed of deciding whether a briefly presented digit was part of a comparison set and gave data from trials on which the comparison set had contained one, three,...

In Chapter 2, I presented data on the speed of deciding whether a briefly presented digit was part of a comparison set and gave data from trials on which the comparison set had contained one, three, or five digits. Eventually, I would like to compare the three conditions (using only the data from trials on which the stimulus digit had in fact been a part of that set), but I worry that the trials are not independent. If the subject (myself) was improving as the task went along, he would do better on later trials, and how he did would in some way be related to the number of the trial. If so, we would not be able to say that the responses were independent. Using only the data from the trials labeled Y in the condition in which there were five digits in the comparison set, obtain the regression of response on trial number. Was performance improving significantly over trials? Can we assume that there is no systematic linear trend over time?