Demonstrations of the Ease of Detecting Additions over Deletions

Abstract

A common generalisation in cognitive psychology is that positive information is often easier to process than negative information. Although not an absolute fi nding in all cases, many studies have found a cognitive bias in favour of processing positive information in diverse areas of psychology. For example, visual search is easier when detecting a feature's presence rather than absence (Neisser, 1963; Treisman and Gormican, 1988; Treisman and Souther, 1985), proofreading is easier when detecting added rather than deleted letters (Healy, 1981), conditional reasoning is more likely to include searches for positive than for negative evidence (Klayman and Ha, 1989;Wason and Johnson-Laird, 1972), sentencepicture verifi cation is faster for positively-stated sentences than for negatively-stated sentences (Clark and Chase, 1972) and positive affective information is better retained in memory as people age than is negative information (Mather, 2003;Mather and Carstensen, 2003).The general nature of this cognitive bias for processing positive information makes it an excellent topic for discussing in a wide variety of psychology courses, including introductory psychology, cognitive psychology, experimental psychology, sensation and perception, learning and memory, and the psychology of language. In fact, the author of a popular textbook in cognitive psychology (Matlin, 2002) uses this cognitive bias as one of the themes for her book. Thus, the relative ease of processing positive information may be used as one of several guiding principles to help students organise their learning about psychological processes.A simple example of the superiority of processing positive information is that people notice the presence of added features (additions) in a previously seen picture more readily than the absence of deleted features (deletions; Agostinelli et al., 1986;Hearst, 1991;Pezdek et al., 1988;Treisman, 1986). The ease of noticing additions over deletions also occurs with verbal stimuli (Maki, 1989). The relative ease of detecting additions compared to deletions can be used in at least two ways in the classroom: to introduce the general topic of a bias in favour of processing positive information by giving students concrete examples; and to stimulate further discussion of more complex instances after using simple, concrete examples.Thus, the purpose of these demonstrations is to introduce in a simple but graphic way that we mentally process positive information differently than we do negative information. Instructors may follow the initial demonstrations with more detailed discussions as they see fi t.We describe three simple and inexpensive methods for demonstrating the ease of detecting additions over deletions. Although each demonstration focuses on a particular topic related to the superiority of noticing additions, each demonstration can easily be used to generate discussions of cognitive bias for processing positive information in any applicable area of psychology. Demonstration 1: modifying the classroom schema