Dissertation

The representation of colour in episodic object memory: evidence from a recognition-induced forgetting paradigm

Williams, Kate Elizabeth

2014

Overview

Empirical evidence suggesting colour influences object recognition is mixed; leading to conclusions that colour may not always be represented in object memory. Positive evidence for the representation of colour in episodic object memory is often complicated by the possibility that encoding specificity may be responsible for such observations. The current thesis examined whether colour is represented and makes an independent contribution of shape in episodic memory for familiar and novel objects, using a modified paradigm based on the typical retrieval- practice task (e.g., Anderson, Bjork, & Bjork, 1994). Participants studied pictures of objects, presented one at a time. In a subsequent practice phase, participants either performed Old/New recognition with a subset of the studied objects and their distractors (Experiments 1-7), or they rated a subset of the studied objects for attractiveness, complexity, and usefulness (Experiments 8 and 9). The critical manipulation concerned the nature of unpracticed objects. Unpracticed objects shared either shape only (Rp- Shape), colour only (Rp-Colour), both shape and colour (Rp-Both), or neither shape nor colour (Rp-Neither), with the practiced objects. Interference effects in memory between practiced and unpracticed items are revealed m the forgetting of related unpracticed items - retrieval-induced forgetting (RIF). If both shape and colour information is explicit in the object representations in episodic memory, then there would be significant RIF for unpracticed objects sharing shape only and colour only with the practiced objects. RIF was significant for Rp-Shape and Rp-Colour objects, suggesting that shape and colour are represented and independently drive competition effects in episodic object memory. The use of RIF to probe those representations improves on previous evidence, because it bypasses alternative encoding specificity explanations. The current work provides proof of concept for a modified retrieval-practice paradigm and establishes it as a tool to probe feature- based representations that do not easily lend themselves to retrieval practice.

• Publisher: ProQuest Dissertations & Theses