Experience with research paradigms relates to infants' direction of preference

Interpreting and predicting direction of preference in infant behavioral research has been a thorny issue for decades. Several factors have been proposed to account for familiarity and novelty preferences in habituation and familiarization studies, including infant age, length of exposure and task complexity. The current study explores an additional dimension that may affect direction of preference: amount of experience with the experimental task. To test this hypothesis, we re-analyzed the data from 4 experiments on artificial grammar learning in 12-month-old infants run using the Head- turn Preference Procedure (HPP). The participants in these studies varied substantially in their number of laboratory visits. Linear mixed-effects results show that the number of HPP studies in which infants had previously participated is related to infants’ direction of preference: infants who had no (or limited) experience with the HPP setting were more likely to show familiarity preferences than infants who had amassed more experience with this task in prior study visits. Interestingly, the effect is driven by a significant decrease in looking time for familiar trials. These results have important implications for the interpretation of experimental results: infants’ experience with a given paradigm or, more broadly, with the lab environment, may affect their patterns of preferences.