A novel method to investigate how dimensions interact to inform perceptual salience in infancy

How physical dimensions govern children’s perception, language acquisition and cognition is an important question in developmental science. Here we use the psychophysical technique of Maximum Likelihood Conjoint Measurement (MLCM) as a novel approach to investigate how infants combine information distributed along two or more dimensions. MLCM is based on a signal detection model of decision that allows testing of several models of how observers integrate information to make choices. We tested 6-month-old infants’ preferential looking to “green” stimuli that covaried in lightness and chroma and analysed infant preferences using MLCM. The findings show that infant looking is driven primarily by lightness, with darker stimuli having a greater preference than lighter, plus a small but significant positive contribution of chroma. This study demonstrates that the technique of MLCM can be used in conjunction with preferential looking to investigate the salience of physical dimensions during development. The technique could now be applied to investigate the role of physical dimensions in key aspects of perceptual and cognitive development such as face recognition, language acquisition and object recognition.