Yellow strawberries and red bananas: The influence of object-colour knowledge on emerging object representations in the brain

The ability to rapidly and accurately recognise complex objects is a crucial function of the human visual system. Successful object recognition requires binding incoming visual features such as colour and form into specific neural representations that can be compared to our pre-existing knowledge about the world. Some objects have typical or implied colour as a central feature that is useful for recognition; for example, a banana is typically yellow. In the current study, we address two main questions. First, we test how colour representations unfold over time when activated by real colour perception versus the activation of implied colours. Second, we examine how features such as colour and form are bound together. We apply multivariate pattern analyses to time-resolved neuroimaging (magnetoencephalography) data to address these questions. Our results show that colour representations can be accessed both via real colour perception and via implied colour activation in the complete absence of colour in the stimulus. These real and implied colour representations share characteristics but differ in the timing of their neural activation. In addition, our data demonstrate that object representations are influenced by object-colour knowledge at later, but not at initial stages of visual processing. Single object features are processed before feature-binding occurs which allows for a comparison of visual input with existing knowledge about objects. Taken together, these results provide new insights into the integration of incoming visual information with existing conceptual object knowledge.