Abstract: A response to a visual target presented at a precued spatial location is facilitated if the target is presented shortly after the cue and inhibited when the cue target onset asynchrony approaches a few hundred ms. The latter effect is termed inhibition of return (IOR). Tipper et al (1991) found that IOR not only existed in static but also in dynamic displays. In particular, when a cued object moves away from the originally cued location, people are slower to detect stimuli in the cued object at its new location. Tipper et al termed this phenomenon object-based IOR. Robertson et al (2001, 2004) , however, suggested that this effect could be reinterpreted as spatial reorienting processes. The present study aimed to examine whether object-based IOR in dynamic displays was resulted from the updating of the spatial inhibition or the inhibition of object representation.
Method
Two experiments were conducted with 36 participants aged 19 to 23 years of age. All participants were naive to the purpose of the experiment and had normal or corrected-to-normal vision. Stimulus presentation and data collection were controlled by an IBM microcomputer running E-prime software. In experiment 1, we examined whether the IOR effect in dynamic displays was independent of the change of landmarks (objects). In experiment 2, by contrasting the response time under the two conditions: 1) no change-valid cued location and 2) change cued object-valid cued location, as an index of object-based IOR, we examined whether the object-based and location-based mechanisms can co-contributed to the IOR in dynamic displays.
Results
The results of experiment 1 showed that IOR was present even when the landmarks had been changed. The results of experiment 2 showed that there was no difference between no change-valid cued condition and change cued object-valid cued condition.
Conclusions
From the results of the present study, it appears that the landmarks changed or not has no influence on the IOR in dynamic displays (experiment 1). There is no evidence that the object-based and location-based mechanisms can co-contributed to the IOR in dynamic displays (experiment 2). In sum, the results showed that the object-based IOR in dynamic displays was resulted from the updating of the spatial inhibition rather than the object inhibition

Key words: dynamic displays, object-based inhibition of return, updating of the spatial inhibition