Illustration is a notoriously difficult thing to measure in this context and various studies have been undertaken to find a correlation between the two and what the link actually is.
An observational study of six children carried out by Feathers & Arya (2012) found that adapted texts with repeated use of elements within the illustrations were much less effective than the authentic versions.
This was determined by measuring the gaze and recall of children during a study where 2 groups of 3 children were given a different version of the same story. One book was the original (authentic) version and the other was adapted. The latter had illustrations taken from the original condensed, re-sized and used less frequently than the authentic book.
The study noted that the illustrated text in its original form was the most effective. This was apparent in recalls where certain assumptions were made based on the illustrations, even when those events hadn’t been referenced or mentioned in the text.
This is particularly interesting in relation to my own work as this non-verbal narration is what I’d like to explore. This study has made me question the relationship between words and pictures and how this non-mirrored dual narration can be used to create a multi-sensory experience in one book.
FEATHERS, K.M. & Arya, P. (2012), ‘The Role of Illustrations During Children’s Reading.’ Journal of Children’s Literature. 38 (1). p. 36.