What’s The Mechanism Of Object Substitution Masking: One-object Morphing Or Two-object Interference?

Visual masking has been widely researched both as a tool to explore awarenessand as a visual phenomenon itself in the field of vision. Object substitution maskingwas first reported by Enns and Di Lollo as a new form of visual masking in1997.Different with other forms of masking, a mask consist of four dots can even beeffective only if in delayed offset condition. The researches about OSM focus mainlyon its functional effect, the mechanism,etc. There’re especially many different viewabout the mechanism of OSM. Researchers explore this matter via behavioralexperiments and electrophysiological methods, but hold different views, such as thefamous reentrant process model，the feedforward model，object updating theory，etc. This study mainly focus on the object updating theory and the two object interferetheory. The author seek to find out which of the two theory has more explanatorypower via three behavioral experiments.Experiment1follows the second experiment in the study of Lleras and Moore（2003）.Compared with the search array，the mask array has an offset in location.The ISI was controled to induce the apparent motion between the two array to explorewhether can we capture masking under the condition that mask array share a differentlocation with the search array. Consistent with the result of Lleras and Moore, therewas still object substitution masking even when the ISI was30ms,and masking wasabsent when the ISI was220ms.The result was in support with the single-objectmorphing mechanism in object updating theory, according to which, apparent motionconnect the single object identity of search array and mask array.The second was designed to make up the first one. The author aim to explore theimpact of the offset of mask array on OSM on the basis of no ISI. We add twoadditional conditions of offset-inward and no offset to completely study this problem，and found that there was still strong masking when ISI was all0ms and with noapparent motion perception. And the masking effect was not dominated by whetheroffset or the orientation of offset. There were no difference among the threeconditions. The two object interference theory has stronger explanation power in comparison with single object morphing theory.In the third experiment, the mask’s color was changed to individuate therepresentation of the mask array and target, thus to explore its impact on OSM effect.It was found that there were still robust masking even though the representation wasseparated. According to the two object theory, the two representations compete witheach other for attention resources, the latter representation interfere with the former,thus, leading to masking.Summarized as follows:(1) There’re actually components in the object levelbesides the image level, and the former plays a more important role.(2)There existstwo object interference mechanism besides one object morphing mechanism.(3)In thisbackground, the whole study in support of the two object theory. In the object level,the main reason of masking is that the representation of mask interfere with the target’for attention resources.