Is the Levels of Processing effect language-limited?

• The levels of processing effect is largely based on words.
• We demonstrate consistent but modest effects using visual stimuli.
• In contrast verbal effects vary widely in magnitude.
• We apply Gibson’s concept of affordance to both visual and verbal stimuli.
• This results in a levels of processing framework that is applicable to both.

The concept of Levels of Processing (LOP), proposing that deep coding enhances retention, has played a central role in the study of episodic memory. Evidence has however been based almost entirely on retention of individual words. Across five experiments, we compare LOP effects between visual and verbal stimuli, using judgments of pleasantness as a method of inducing deep encoding and a range of shallow encoding judgments selected so as to be applicable to both verbal and visual stimuli. LOP effects were consistent but modest across the visual stimuli (mean effect size 0.5). In contrast, LOP effects for verbal stimuli varied widely, from modest for people’s names and unfamiliar animals (mean effect size 0.6) to large for familiar animals and household items (mean effect size 1.4), typical of the dramatic LOP effects that characterize the existing verbal literature. We interpret our data through the Gibsonian concept of “affordance”, proposing that visual and verbal stimuli vary in the number and richness of features they afford, and that access to such features will in turn depend on encoding strategy. Our hypothesis links readily with Nairne’s feature model of long-term memory.