Humans strategically shift decision bias by flexibly adjusting sensory evidence accumulation

Niels A. Kloosterman, Jan Willem de Gee, Markus Werkle-Bergner, Ulman Lindenberger, Douglas D. Garrett, Johannes Jacobus Fahrenfort

Research output: Contribution to JournalArticleAcademicpeer-review


Decision bias is traditionally conceptualized as an internal reference against which sensory evidence is compared. Instead, we show that individuals implement decision bias by shifting the rate of sensory evidence accumulation toward a decision bound. Participants performed a target detection task while we recorded EEG. We experimentally manipulated participants' decision criterion for reporting targets using different stimulus-response reward contingencies, inducing either a liberal or a conservative bias. Drift diffusion modeling revealed that a liberal strategy biased sensory evidence accumulation toward target-present choices. Moreover, a liberal bias resulted in stronger midfrontal pre-stimulus 2-6 Hz (theta) power and suppression of pre-stimulus 8-12 Hz (alpha) power in posterior cortex. Alpha suppression in turn was linked to the output activity in visual cortex, as expressed through 59-100 Hz (gamma) power. These findings show that observers can intentionally control cortical excitability to strategically bias evidence accumulation toward the decision bound that maximizes reward.

Original languageEnglish
Article numbere37321
Pages (from-to)1-27
Number of pages27
Publication statusPublished - 6 Feb 2019


  • decision bias
  • drift diffusion modeling
  • electroencephalography
  • human
  • neural excitability
  • neural oscillations
  • neuroscience
  • perceptual decision-making


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