The Role of Premature Evidence Accumulation in Making Difficult Perceptual Decisions under Temporal Uncertainty

Abstract

The computations and neural processes underpinning decision making have primarily been investigated using highly simplified tasks in which stimulus onsets cue observers to start accumulating choice-relevant information. Yet, in daily life we are rarely afforded the luxury of knowing precisely when choice-relevant information will appear. Here, we examined neural indices of decision formation while subjects discriminated subtle stimulus feature changes whose timing relative to stimulus onset ('foreperiod') was uncertain. Joint analysis of behavioral error patterns and neural decision signal dynamics indicated that subjects systematically began the accumulation process before any informative evidence was presented, and further, that accumulation onset timing varied systematically as a function of the foreperiod of the preceding trial. These results suggest that the brain can adjust to temporal uncertainty by strategically modulating accumulation onset timing according to statistical regularities in the temporal structure of the sensory environment with particular emphasis on recent experience.

Temporal Expectation Hastens Decision Onset But Does Not Affect Evidence Quality

“…In contrast, valid and invalid trials did not differ in CPP slope, suggesting that temporal expectation did not affect the quality of the sensory evidence or other processes influencing the rate of decision formation. Control analyses excluded premature sampling of the stimulus array prior to target onset (Jepma et al, 2012;Laming, 1979;Devine et al, 2019) as an alternative explanation of these results. EEG α-band power is thought to reflect local cortical excitability (Jensen & Mazaheri, 2010;Pfurtscheller, 2001) and has previously been shown to track temporal expectations, enhancing perception of events occurring at expected moments (Heideman et al, 2018;Rohenkohl & Nobre, 2011;Zanto et al, 2011).…”

“…premature sampling (of noise) on a proportion of the trials Laming, 1979;Devine et al, 2019). That is, participants may anticipate the arrival of a target stimulus and speed up responses by starting to sample information from the display at the moment when they think the stimulus will be presented.…”