Alpha and gamma band oscillations index differential processing of acoustically reduced and full forms

• Alpha and gamma oscillations are modulated by a word’s pronunciation variant.
• Alpha shows higher cognitive load for reduced forms in non-mid-sentence position.
• Gamma activity reflects activation of semantic networks.
• Gamma activity shows delayed spreading through semantic networks for reduced forms.
• Processing advantage for full words, especially in non-mid-sentence position.

Reduced forms like yeshay for yesterday often occur in conversations. Previous behavioral research reported a processing advantage for full over reduced forms. The present study investigated whether this processing advantage is reflected in a modulation of alpha (8–12 Hz) and gamma (30+ Hz) band activity. In three electrophysiological experiments, participants listened to full and reduced forms in isolation (Experiment 1), sentence-final position (Experiment 2), or mid-sentence position (Experiment 3). Alpha power was larger in response to reduced forms than to full forms, but only in Experiments 1 and 2. We interpret these increases in alpha power as reflections of higher auditory cognitive load. In all experiments, gamma power only increased in response to full forms, which we interpret as showing that lexical activation spreads more quickly through the semantic network for full than for reduced forms. These results confirm a processing advantage for full forms, especially in non-medial sentence position.