The sensory enhancement theory assumes that attentional resources will spread until they reach the boundaries of a cued object, including regions that may be obstructed or are overlapping other objects. It has been suggested that sensory enhancement is an essential mechanism that underlies object-based attention. The sensory enhancement theory of object-based attention proposes that when attention is directed to a cued object, the quality of the object’s physical representations improve because the spread of attention facilitates the efficiency of processing the features of the object as a whole. The qualities of the cued object, such as spatial resolution and contrast sensitivity, are therefore more strongly represented in one's memory than the qualities of other objects or locations that received little or no attentional resource. Information processing of these objects also tends to be significantly faster and more accurate as the representations have become more salient. Evidence of sensory enhancement Single-cell recordings Single-cell recordings experiments were the first experiments to support the presence of sensory enhancement. V1 neurons in monkeys were measured for neural responses by Roelfsema, Lamme & Spekreijse (1998), while the monkeys performed a curve-tracing task. The neurons were found to be more active when their receptor fields were on the target-curve as opposed to when their receptor fields fell on the distractor-curve. Furthermore, enhancement was present in the neurons whose receptor fields were on segments of the target-curve relative to segments of the distractor-curve. This effect occurred regardless of whether the curves were spatially separate or overlapping. The presence of neural enhancement when the neurons receptor fields fell on the target-curve could suggest that attention is spreading to the boundaries of the object and then stopping. More recently, Roelfesema and Houtkamp (2011) found that there was a time difference in the onset of enhancement in these V1 neurons. The enhancement of the neuron took longer to appear as the spatial distance between the fixation of attention and receptor field increased. This finding is supported by the performance of mental curve tracing tasks in humans. The results of these single cell recording studies therefore suggest that attention when deployed within an object enhances the representations of the object as a whole and this process of enhancement is gradual so it takes time to complete. Attention to an object or surface has been directly linked by Wannig, Rodrίguez and Freiwald (2007) to increased neural activation of representations in the early