Evidence from many different paradigms (e.g. change blindness, inattentional blindness, transsaccadic integration) indicate that observers are often very poor at reporting changes to their visual environment. Such evidence has been used to suggest that the spatio-temporal coherence needed to represent change can only occur in the presence of focused attention. In four experiments we use modified change blindness tasks to demonstrate (a) that sensitivity to change does occur in the absence of awareness, and (b) this sensitivity does not rely on (...) the redeploy- ment of attention. We discuss these results in relation to theories of scene percep- tion, and propose a reinterpretatio n of the role of attention in representing change. (shrink)

& Awareness of change within a visual scene only occurs in subjects were aware of, replicated those attentional effects, but the presence of focused attention. When two versions of a.

b>—Several paradigms (e.g. change blindness, inattentional blindness, transsaccadic integra- tion) indicate that observers are often very poor at reporting changes to their visual environment. Such evidence has been used to suggest that the spatio-temporal coherence needed to represent change can only occur in the presence of focused attention. However, those studies almost always rely on explicit reports. It remains a possibility that the visual system can implicitly detect change, but that in the absence of focused attention, the change does not (...) reach awareness and consequently is not reported. To test this possibility, we used a simple change detection paradigm coupled with a speeded orien- tation discrimination task. Even when observers reported being unaware of a change in an item’s orientation, its nal orientation effectively biased their response in the orientation discrimination task. Both in aware and unaware trials, errors were most frequent when the changed item and the probe had incongruent orientations. These results demonstrate that the _nature _of the change can be represented in the absence of awareness. (shrink)

This volume will be an invaluable guide for student and professional researchers in visual perception, cognitive psychology, and cognitive neuroscience.

Several recent findings support the notion that changes in the environment can be implicitly represented by the visual system. S. R. Mitroff, D. J. Simons, and S. L. Franconeri (2002) challenged this view and proposed alternative interpretations based on explicit strategies. Across 4 experiments, the current study finds no empirical support for such alternative proposals. Experiment 1 shows that subjects do not rely on unchanged items when locating an unaware change. Experiments 2 and 3 show that unaware changes affect performance (...) even when they occur at an unpredictable location. Experiment 4 shows that the unaware congruency effect does not depend simply on the pattern of the final display. The authors point to converging evidence from other methodologies and highlight several weaknesses in Mitroff et al.’s theoretical arguments. It is concluded here that implicit representation of change provides the most parsimonious explanation for both past and present findings. (shrink)

Local motion is known to produce strong illusory displacement in the perceived position of globally static objects. For example, if a dot-cloud or grating drifts to the left within a stationary aperture, the perceived position of the whole aperture will also be shifted to the left. Previously, we used a simple tracking task to demonstrate that active control over the global position of an object did not eliminate this form of illusion. Here, we used a new iPad task to directly (...) compare the magnitude of illusory displacement under active and passive conditions. In the active condition, participants guided a drifting Gabor patch along a virtual slalom course by using the tilt control of an iPad. The task was to position the patch so that it entered each gate at the direct center, and we used the left/right deviations from that point as our dependent measure. In the passive condition, participants watched playback of standardized trajectories along the same course. We systematically varied deviation from midpoint at gate entry, and participants made 2AFC left/right judgments. We fitted cumulative normal functions to individual distributions and extracted the point of subjective equality (PSE) as our dependent measure. To our surprise, the magnitude of displacement was consistently larger under active than under passive conditions. Importantly, control conditions ruled out the possibility that such amplification results from lack of motor control or differences in global trajectories as performance estimates were equivalent in the two conditions in the absence of local motion. Our results suggest that the illusion penetrates multiple levels of the perception-action cycle, indicating that one important direction for the future of perceptual illusions may be to more fully explore their influence during active vision. (shrink)