Some questions to consider for your introduction:
1) Why are these stimulus dimensions considered separable? Is there any evidence for that? (Note that similar stimuli have been used previously in experiments by Shepard, 1964, to provide a measure of their separability. Others have also used these stimuli – albeit for different purposes and have assumed that they are separable; e.g., Nosofsky, 1986; Ashby & Maddox, 1990; Ashby & Lee, 1991; Stewart, Brown & Chater, 2002).
2) What is the additive factors paradigm and what question is it designed to answer? Why is this important/useful?
3) Based on the previous results, what type of processing do we expect for these stimuli? (Hint: a good summary of a related experiment would be Little, Nosofsky, Donkin & Denton, 2013, Experiment 2).
4) Is there any additional information in the data that might help us make our decision? (Hint: See Fific, Little & Nosofsky, 2010, p. 315)
5) How does this method compare with other methods designed to tell us how features are processed? (e.g., visual search)
6) You’ll need to provide the hypothesized predictions for each of the candidate models. What are these models? What predictions do they make? How will we test these predictions?