Many experiments require counterbalancing sequences of trials. For example, I’m currently running an experiment on serial dependence1. In my experiment, participants report the orientation of a grating2 stimulus on each trial. The serial dependence effect is how their responses on one trial depend on either the orientation of the previous trial or their response on that trial. To tease apart the effects of prior stimuli from prior responses, I’m manipulating the visual contrast of the gratings ( Michelson contrast ).
I’ve started trying out MATLAB’s OOP after mounting suspicion that the way I’d been coding experiments basically involved making something that looked and behaved like an object–but did so in a convoluted and inefficient way. See this post on eyetracking with PTB as proof.
This post is brief, and is about as well thought out as a github gist/gitlab snippet.
The two classes I’ll work with here is a Window class and a Tracker class.
It may be the case that Amazon Mechanical Turk WorkerIDs are not anonymous. Lease et al., 2013 describe at length how personally identifying information may be exposed when a researcher shares WorkerIDs. It is unclear to me the extent to which Amazon constructs their WorkerIDs at present, given that one of their striking demonstrations did not apply to my WorkerID. That is, they describe simply googling the WorkerID and receiving a picture of the participant, along with their full name.
UPDATE: I now think that the examples I’ve presented here obscure the interface with Eyelink. Much cleaner to use MATLAB’s object oriented programming. This is covered in another post.
This post is designed as minimal documentation for using the Eyelink software at the UMass Amherst hMRC. The goals are very modest
Provide sample Psychtoolbox (PTB) and MATLAB code for integrating eyelink Explain a few parameters that you might want to change in your experiment The main audience includes members of the cMAP and CEMNL labs at UMass, but other users of the hMRC may also benefit.