Perceptual narrowing is characterized by a fast attunement of discriminatory abilities to specific sensory input that infants encounter in their daily life. This process corresponds to declining discrimination for stimuli not present or relevant in the environment of the infant. Perceptual narrowing has been studied especially for face and speech discrimination and indicated similar developmental trajectories (see for a review, Maurer & Werker, 2014). However, infants´ face and speech processing has almost been studied separately. Therefore, the aim of the project is to investigate the perceptual narrowing during the first year of life in an interdisciplinary approach regarding the processing of visual and auditory modalities. Central research questions are whether the mechanisms of face and speech discrimination rely on a domain-general or on a domain-specific processing, and whether there are differences in conditions of modifying perceptual narrowing in speech and face recognition at an age in which perceptual narrowing seems to be set. Specially, we focus on the recognition of own-race vs. other-race faces, the discrimination of speech sounds, and the face and voice matches. Developmental changes will be measured with eye-tracking and ERPs to gain insights into whether the same mechanisms are involved in the processing of information in the different domains. To investigate these mechanisms we conduct two series of studies. The first series will focus on the timing and strength of perceptual narrowing of face and speech recognition in a longitudinal and cross-sectional study with infants between the ages of 6 and 9 months. The second series will focus on the feasibility of modifying the perceptual narrowing and its conditions at a later age (9 and 12 months).