| Summary: | The time required to identify a common object depends on several factors,
especially pre-existing knowledge and episodic representations newly established as a
result of a prior study. My research examined how these factors contribute to
identification of objects (both studied and non-studied) and to performance on explicit
memory tests. The overall goal was to explore the link between memory and object
perception.
One series of experiments examined influences due to object orientation in the
plane of the page. Subjects were shown color photos of objects, and memory was assessed either with an old/new recognition test or with a test that required them to
identify objects that were slowly faded in on a computer monitor. The critical variables
were the type of photo — each showing either an object with a predominant or cardinal
orientation (e.g., helicopter) or a non-cardinal object (e.g., pencil), and the orientation at
which the photos were displayed at study and at test (e.g., rotated 0°, 120°, or 240°). For
non-studied targets, identification test performance showed a large effect due to display
orientation, but only for cardinal objects. For studied targets, study-to-test changes in
orientation influenced priming for both non-cardinal and cardinal objects, but orientation
specific priming effects (larger priming when study and test orientations matched rather
than mismatched) were much larger with cardinal than non-cardinal objects, especially,
when their display orientation, at test was unusual (i.e., 120°, 240°).
A second series of experiments examined influences due to object size (size of an
object presented alone) and relative size (size of an object relative to another object).
Size manipulations had a large effect on identification of non-studied objects but study-to-
test changes in size had only a minimal effect on priming. In contrast, study1to-test
changes in relative size influenced recognition decision speed which is an index of
priming.
The combined findings suggest that both semantic and episodic representations
behave as if they coded orientation but only for cardinal objects. They also suggest that
episodic representations code relative size but not size information. The findings are
explained by the instance views of memory.
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