How to Compare Apples and Oranges: Infants' Object Identification Tested With Equally Salient Shape, Luminance and Color Changes.

What kind of featural information do infants rely on when they are trying to recognize a previously seen object? The question of whether infants use certain features (e.g. shape or color) more than others (e. g. luminance), can only be studied legitimately if visual salience is controlled, since the magnitude of feature values - how noticeable and interesting they are - will affect results. We employed a novel methodology, 'Interdimensional Salience Mapping', that allowed us to quantify and calibrate salience changes along shape, luminance and color feature dimensions. We then compared 9-month-old infants' identification of objects, employing feature changes that were equally salient. These results show that infants more readily identify objects on the basis of color and shape than luminance. Additionally, we show that relative salience changes rapidly in infancy - in particular, we found significantly higher salience thresholds for color in younger (6.5-month-old) infants - but that individual differences within an age group are remarkably modest.