No evidence of neural feature-specific pre-activation during the prediction of an upcoming stimulus
Our brains constantly make predictions about upcoming events based on prior knowledge of the environment. Although several neural mechanisms have been proposed to support this capacity, it is not yet clear how the brain makes such predictions. A compelling hypothesis is that the brain preactivates a sensory template of a predictable stimulus before it appears. In a recent study, Demarchi et al. had participants listen to sequences of sounds with different levels of predictability. For some sequences, participants could anticipate the next sound (in regular sequences), for others not (in random sequences). Using magnetoencephalography recordings and machine-learning methods to decode sounds from brain signals, Demarchi et al. concluded that auditory predictions pre-activate tone-specific neural templates before the sound onset. In our reanalysis of their data, we demonstrate that their results can be fully explained by a bias induced by the structure of the sequences: because the most likely stimulus also happens to be physically close to the previous one, spurious higher-than-chance decoding performance arises before the sound onset. We provide general criteria to assess whether a study is affected by this confound and requires a reexamination. We conclude that there is no evidence of anticipatory predictive perception in the Demarchi et al. dataset, and that existing evidence for feature-specific pre-activation during prediction in humans remains inconclusive.