Inference with interference between units in an fMRI experiment of motor inhibition

TL;DR

This paper addresses the challenge of making valid inferences in fMRI experiments where interference occurs between units, such as stimuli affecting subsequent responses, by developing and evaluating new statistical methods.

Contribution

It introduces and applies new methodology for inference in experiments with interference between units, specifically in the context of fMRI studies of motor inhibition.

Findings

Simulation shows improved power of the proposed procedures.

Method effectively accounts for interference in fMRI data.

Enhances validity of inferences in cognitive neuroscience experiments.

Abstract

An experimental unit is an opportunity to randomly apply or withhold a treatment. There is interference between units if the application of the treatment to one unit may also affect other units. In cognitive neuroscience, a common form of experiment presents a sequence of stimuli or requests for cognitive activity at random to each experimental subject and measures biological aspects of brain activity that follow these requests. Each subject is then many experimental units, and interference between units within an experimental subject is likely, in part because the stimuli follow one another quickly and in part because human subjects learn or become experienced or primed or bored as the experiment proceeds. We use a recent fMRI experiment concerned with the inhibition of motor activity to illustrate and further develop recently proposed methodology for inference in the presence of interference. A simulation evaluates the power of competing procedures.