Strength of object representation: its key role in object-based attention for determining the competition result between Gestalt and top-down objects

Unraveling the mechanism of semantic object-based attention: The role of top-down search strategies

There is an ongoing debate between the sensory enhancement account and the attentional prioritization account concerning the mechanism underlying object-based attention. This debate remains unresolved because of the predominant use of geometric objects in previous studies, which made it difficult to experimentally dissociate the two accounts due to the prominent boundaries of these objects. The current study investigated the mechanism underlying semantic object-based attention by utilizing Chinese two-character words with different word frequencies and the event-related potentials (ERPs) technique to elucidate the ongoing debate. The behavioral results showed that the semantic object effect was observed only in the high-frequency condition. The ERP results revealed the following: (1) the N1 component was larger for the high-frequency condition compared with the low-frequency condition. However, there was no significant difference in amplitude between the N1 component elicited by invalid same object locations and invalid different object locations, irrespective of whether it occurred in high- or low-frequency conditions. (2) The P3 component elicited by invalid same object locations was larger than that elicited by invalid different object locations only in the high-frequency condition. (3) The N400 amplitude elicited by invalid same object locations was smaller than that elicited by invalid different object locations only in the high-frequency condition. These results suggest that in the absence of obvious object boundaries, the production of object-based attention is primarily driven by search strategies. Attentional prioritization, rather than sensory enhancement, is the dominant mechanism underlying object-based attention.

Object-based inhibition of return in three-dimensional space: From simple drawings to real objects

Cued to an object in space, inhibition of the attended location can spread to the entire object. Although object-based inhibition of return (IOR) studies in a two-dimensional plane have been documented, the IOR has not been explored when objects cross depth in three-dimensional (3D) space. In the present study, we used a virtual reality technique to adapt the double-rectangle paradigm to a 3D space, and manipulated the cue validity and target location to examine the difference in object-based IOR between far and near spaces under different object representations. The study showed that the object-based IOR of simple drawings existed only in near space, whereas object-based IOR of real objects existed only in far space at first, and as the object similarity decreases, it appeared in both far and near spaces.

Neutral animals matter: Animacy modulates object-based attentional allocation

Animacy plays an essential role in survival and adaptive behaviour. Previous studies have found that dangerous or threatening animals can capture and hold attention. However, it is unclear whether and how neutral animate objects guide attentional allocation. It is also uncertain whether the modulation of animate objects on attentional allocation is based on the object itself (object-based attention) or its location (space-based attention). Therefore, the present study adopted the well-established two-rectangle paradigm and used animate and inanimate objects as stimuli to test the abovementioned problems. The results revealed that object-based effects were obtained for both animate and inanimate objects. However, the object-based effects were larger when the cue appeared on the animate objects than on the inanimate objects, due to faster response to invalid same-object trials and slower response to invalid different-object trials. Beyond that, we also further confirmed that animacy itself, not the low-level visual complexity, led to the differential object-based effects. These results suggest that neutral animals also mattered to our attentional allocation and animacy can modulate object-based attentional selection by capturing and holding visual attention on the animate objects. Ultimately, the present study not only enriches our understanding of how neutral animate objects guide attentional allocation and support the attentional prioritisation theory, but also further extends and amends the animate-monitoring hypothesis.

Attention can operate on object representations in visual sensory memory

Numerous studies have shown that attention can be allocated to various types of objects, such as low-level objects developed by perceptual organization and high-level objects developed by semantic associations. However, little is known about whether attention can also be affected solely by object representations in the brain, after the disappearance of physical objects. Here, we used a modified double-rectangle paradigm to investigate how attention is affected by object representation in visual sensory memory when the physical objects disappear for a short period of time before the target onset. By manipulating the interstimulus interval (ISI) between the offset of the objects and the onset of the target, an object-based attention effect, with shorter reaction times (RTs) for within-object relative to between-object conditions, was observed in the short-ISI (within 500 ms in Experiments 1a, 1b, 2, and 3) conditions while disappearing in the long-ISI (800 ms in Experiment 4) conditions. This result demonstrated that the mere presence of object representation in visual sensory memory, or the sensory memory-maintained object, can serve as an object unit that attention can operate on. This provides evidence for the relationship between object-based attention and visual sensory memory: object representation in visual sensory memory could affect attentional allocation, or attention can operate on a sensory memory-maintained object.

The influence of object similarity on real object-based attention: The disassociation of perceptual and semantic similarity

Perceptual and semantic similarity have an impact on object-based attention for the geometric objects. However, no previous studies have disassociated perceptual properties from the semantic ones of real objects that combine perceptual and semantic properties. It is unclear whether the perceptual and semantic similarity of real objects jointly or independently guides attentional deployment. The aim of the present study was to explore the influence of object similarity on object-based attention by using a variant of the two-rectangle paradigm and disassociating the perceptual and semantic similarity of real objects. The results indicated that when the semantic of objects was similar, the object-based effect was larger for the perceptually dissimilar condition than for the perceptually similar condition, because of slower response to invalid different-object location in a dissimilar condition. Moreover, when the perception of objects was similar, the object-based effect was larger for the semantically dissimilar condition than for the semantically similar condition, due to slower response to invalid different-object location in a dissimilar condition. These results suggest that perceptual and semantic similarity can independently guide attentional allocation to real objects and the similarity may constrain the object-based attention in a way of grouping. The current study implies that the attentional prioritization hypothesis is more flexible and effective to explain the real object-based attention and also has some implication to advertising design.

The impact of monetary stimuli on object-based attention

Previous research has implied that monetary reward to target location (a reward for spatial properties) can affect object-based attention, but no study has directly investigated the influence of monetary objects (a reward for object properties) on object-based attention. Thus, it is unclear whether and how monetary objects can affect object-based attention. To experimentally investigate this problem, this study adapted the well-established two-rectangle paradigm. In Experiment 1, either two 100-yuan notes or two 1-yuan notes were presented to participants. We found an object-based effect with faster responses to targets at an uncued position on the cued object compared to those at an equidistant position on the uncued object; the effect was similar in 100-yuan and 1-yuan note trials. In Experiment 2, two notes (one 100-yuan and one 1-yuan) were simultaneously presented to participants, and cue location (100-yuan, 1-yuan) was manipulated. We found a greater object-based effect when the cue appeared on the 100-yuan note than on the 1-yuan note. These results suggest that the rewarding property of objects can affect object-based attention by means of altering object salience.