Recent research into the impact of labelling on infants’ visual category formation has led to controversial results, with some findings indicating a beneficial role and others pointing to interference effects in the presence of labels. Here we present an eye tracking study with 12-month-olds investigating the impact of the label’s timing on categorisation. We find that synchronous presentation of words and objects leads to a decreased novelty preference, creating the impression of a dramatic detrimental impact on learning. Asynchronous presentation of the word one second after the image onset does not appear to interfere with processing. Detailed analyses of infants' gaze patterns with respect to object parts reveal that even synchronous labels do not hinder learning but slow down infants' shift from familiarity to novelty preference. Besides offering detailed insight into the effects of labelling on infants' attention our findings offer the potential to reconcile previous contradictory results.