Food flavour often takes time to develop, varies over mouthfuls and indeed over inhalation and exhalation. Despite this, we rarely acknowledge or even perceive such variation. Consider the last chocolate bar you consumed. You likely recall a contiguous chocolate flavour (i.e. non-changing over and even within mouthfuls) but have little or no recollection of any flavour variation. Somehow, a constant food flavour is experienced despite variation in sensory signal. Related processes act in a similar fashion in other modalities (perceptual constancy, e.g. in vision) and across modalities (the unity assumption; Welsh & Warren, 1980). It was hypothesised that a food which is assumed to be consistently flavoured will be tasted to be so, despite some variation in actual flavour. A cookie model-food-stimulus was developed, whose two halves sometimes differed in terms of sweetness (0%, 33% and 67% sugar quantity differences) but were visually indistinguishable (to ensure the assumption of a contiguous cookie). Sweetness ratings for 0% and 33% cookie halves were indistinguishable for early trials; for later trials the 33% cookie halves were rated differently in terms of sweetness from each other. The 67% cookie-halves were always rated differently in terms of sweetness. Our findings provide first support for the existence for a contiguity effect which can mask some flavour variation, but whose effects are modulated by increasing exposure to discrepant stimuli.