Code conflict in an event file task is reflected by aperiodic neural activity

We investigated the relationship between aperiodic electroencephalography (EEG) activity and code conflict, hypothesizing that the former might serve as an indicator of the latter. We analyzed EEG and behavioral outcomes of a sample performing the event file task, which assesses code conflict in co-occurring or temporally overlapping stimulus and response features. To quantify aperiodic activity, we employed the fitting oscillations & one-over-f algorithm. The behavioral results revealed a typical partial-repetition cost effect, indicating that performance is impaired if the stimulus repeats while the response alternates, or vice versa. This suggests that the previously combined shape and response were stored in an event file and retrieved when any one of these components was repeated. Notably, this effect was also evident in the aperiodic exponent, which was lower for partial repetitions than for full repetitions or alternations, implying increased cortical noise, a higher excitatory E/I ratio, and noisier decision-making processes. The scalp distribution of this effect aligns with its sensorimotor characteristics. Thus, we interpret these findings as promising preliminary evidence that the aperiodic exponent may serve as a valuable neural marker of code conflict.