Measures of visual working memory fidelity. (a) A change detection task. Observers see the ‘Study’ display, then after a blank must indicate whether the ‘Test’ display is identical to the Study display or whether a single item has changed color. (b) Change detection with complex objects. In this display, the cube changes to another cube (within-category change), requiring high-resolution representations to detect. (c) Change detection with complex objects. In this display, the cube changes to a Chinese character (across-category change), requiring only low-resolution representations to detect. (d) A continuous color report task. Observers see the Study display, and then at test are asked to report the exact color of a single item. This gives a continuous measure of the fidelity of memory.