3 - Experimental procedure

Summary

The definition of the conditions, tasks, and experimental objects is the initial focus of the experimental design, and must be carefully related to the research question, as described in Chapter 2. The experiment itself could be described simply as presenting the stimuli to human participants and asking them to perform the tasks. There are, however, still many other decisions to be made about the experimental process, as well as additional supporting materials and processes to be considered.

This chapter focuses on the nature of the participant experience, that is, what each participant will do between the start and end times of the experiment – a lot more happens than simply presenting the trials.

Allocating participants to conditions

As highlighted in Chapter 1, the key issue when running experiments is the comparison of performance between the conditions: does one condition produce better or worse performance than another? To determine “performance with a condition,” human participants will need to perform tasks associated with the HCI idea being investigated, and measurements of the overall performance for each condition will be taken. Recall that we want to produce data like that in Figure 2.1, which summarises performance according to each experimental condition, with no explicit reference to tasks or experimental objects.