Many parents and caregivers believe that multi-sensory stimulation during infancy promotes developmental growth and learning, but researchers who conducted eye movement experiments on preverbal infants show that this is not always true.

The team discovered that 8 to 10 month old infants could learn basic abstract rules, such as sequences, but only when the audio and visual stimuli were "congruently" or "consistently" paired. If a smiling face was paired with a crying sound, the infants were confused, and they did not learn the rule.

The findings indicate that having both visual and audio inputs - or more than one sensory stimulation - does not guarantee successful learning. They have to match each others' nature.

"How to match stimulation from visual, audio, tactile, and other sensory systems into a unified manner is the key to help our little ones fully benefit from it," said Dr. Chia-huei Tseng, senior author of the Developmental Science study.

Study: Bimodal emotion congruency is critical to preverbal infants' abstract rule learning, Tsui, A. S. M., Ma, Y. K., Ho, A., Chow, H. M. and Tseng, C.-h., Developmental Science, doi: 10.1111/desc.12319, published online 17 August 2015.