Examining Object-based Attention In Visual Sensory Memory

Object-based attention(OBA)is a visual mechanism that attention could select the object as a unit and paying attention to an object could promote the further process of it.At present,how to define an object in the OBA is still inconclusive.Numerous studies have shown that attention can be allocated to various types of objects,such as low-level objects developed by the perceptual organization and high-level objects developed by semantic associations.However,little is known on whether attention can also be affected solely by object representations in the brain,without the actual presence of any physical objects.This paper would explore this issue thoroughly by three independent studies.In study 1,we used a modified double-rectangle paradigm to investigate how attention was affected by the object representation in visual sensory memory,when the physical objects were disappeared for 0 to 800 ms before target onset.By manipulating the inter-stimulus interval(ISI)between the offset of the objects and the onset of the target,we observed the significant OBA effects when the ISI less than 500 ms while this effect vanished at the 800 ms ISI condition.By conducting the linear fitting of the OBA effects based on objects under each ISI condition,we found that this effect decreased with the extension of ISI and disappeared eventually.This trend is consistent with the decay of object representation in sensory memory over time,which confirmed that OBA effect could be produced by object representation in sensory memory.As the double-rectangle cuing paradigm adopted in study 1 was time-consuming and inefficient,we aimed to develop a more efficient experimental paradigm to study the OBA.Inspired by a modified version of the double-rectangle paradigm,study 2 lucubrate this paradigm and named it as sequential target task.By changing the time interval between two targets and the judgment task,study 2 proved that this paradigm was efficient and repeatable for studying the OBA effect.Study 3 redefined the OBA effect as the time difference between the transfer within the object and the space at the equal spatial distance.By applying the sequential object judgment task developed by study 2 into the single rectangular paradigm,study 3 proved that the vanished object could stably induce the OBA effect,which proved the conjecture of this paper again.In short,this paper provided evidence for the relationship between object-based attention and visual sensory memory—attention can be based on object representations in visual sensory memory,or,attention can operate on sensory-memory-based object.