fMRI Task Design Guide

Purpose

The experimental design is the single most important determinant of an fMRI study's statistical power, interpretability, and scientific value. Choosing between block, event-related, and mixed designs involves trade-offs between detection power and estimation efficiency that depend on the research question. Similarly, the choice of inter-stimulus interval (ISI), jittering strategy, condition ordering, and trial count directly determines whether the BOLD signal of interest can be reliably detected.

A competent programmer without neuroimaging training would not know that block designs provide higher detection power but cannot estimate HRF shape, that exponentially distributed jitter is more efficient than uniform jitter, or that the BOLD response takes 12-16 seconds to return to baseline. This skill encodes those domain-specific design decisions.

When to Use This Skill

• Planning a new task-based fMRI experiment
• Choosing between block, event-related, or mixed designs
• Optimizing inter-stimulus interval and jittering strategy
• Calculating design efficiency for contrast detection
• Determining minimum trial counts per condition
• Integrating behavioral task constraints with fMRI timing requirements
• Reviewing or troubleshooting an existing fMRI task design

Research Planning Protocol