How do we construct organized and meaningful representations of the visual environment from the fragmentary featural information provided by early vision? Recognition--determining the types of objects present in a visual scene--is only half the problem. We also need to be able to establish a separate representation for """"""""object token"""""""") for each instance of an object, specifying that object's position (or trajectory) in space and time. My work on repetition blindness (RB) has demonstrated a fundamental dissociation in human vision between the recognition of visual types and the individuation of visual object tokens. In RB, although the repeated stimulus item is recognized, it is not perceived consciously because it does not get assigned to a new object token. The experiments proposed here investigate the mechanisms of token individuation (Part I) explore what visual processes require token individuation (Part II), and examine the relationship between repetition blindness and other attentional phenomena (Part III). Experiments 1 - 3 investigate why repetition blindness is robust at stimulus presentation rates of 7 or more items/second but nonexistent at 4/second, by exploring the dependence of RB on critical word duration, total memory load, and other factors. Is RB due to the lack of a token altogether, or the lack of a new type-to-token link (Experiment 4)? Is RB reduced or eliminated when the two occurrences are perceived as part of the same object token - because they are either connected behind an occluder (Experiment 5) or connected by apparent motion (Experiment 6)? The answers to these questions will be necessary before a full account of the mechanisms underlying RB can be offered. Part II uses RB to ask what visual processes require object tokens, and explores the nature of the visual """"""""type"""""""" categories underlying repetition blindness. Is token individuation necessary for semantic priming (Experiment 7), scene recognition (Experimetn 9), and feature conjunction (Experiment 10)? Does RB require a preexisting category at all, or will it happen for novel shapes (Experiment 11) or nonwords (Experiment 12)? Part III explores the possible connections between repetition blindness and other attentional phenomena. Experiment 14 asks whether a single very general novelty bias in perception might underlie both RB and novel pop-out. Experiment 15 tests whether it is only new types, or also new object tokens, which automatically pull attention. Experiment 16 asks whether attentionally """"""""blinked"""""""" items will cause negative priming (but not RB).
