Change Blindness and Encoding Failures
Change blindness occurs when people fail to detect changes in objects or scenes that occur over time. In their field study, Levin and Simons had an experimenter ask a research participant on a college campus for directions. In the middle of the conversation, two men walked between them holding a door that temporarily hid the experimenter. Behind the door, the two experimenters changed places so that when the experimenter reappeared, a different person was asking for directions. Less than half (only 7 of 15) of the participants noticed the change! Simons and Levin concluded that people typically encode features of a scene at an extremely shallow level, noting the general gist of the scene but few of the specific details. They note, “Successful change detection probably requires effortful encoding of precisely those features or properties that will distinguish the original from the changed object.”
Having noted that observers who showed change blindness were older adults (college students tended to notice the change), Simons and Levin hypothesized that the older persons may have encoded the initial (young) experimenters simply as “college students,” whereas the college students may have encoded their peers at a more specific level. To test this hypothesis, the experimenters repeated the study, this time attired as construction workers. They reasoned that the college students might now encode them categorically as “construction workers” and, as a result, demonstrate greater change blindness. Indeed, now only 4 of 12 students noticed when a different construction worker emerged from behind the door to ask directions. Shallow encoding that does not go beyond a categorical level produces poor recollection of scene details and greater susceptibility to change blindness. In their review of research on change blindness,
Simons and Ambinder note how individual differences in expertise and culture (as well as age) can affect change-detection performance. For example, experts in American football are better able to detect meaningful changes in football scenes than those who are unfamiliar with the sport. Presumably, expertise guides attention when viewing images, thereby enhancing change detection for semantically meaningful changes.
Having noted that observers who showed change blindness were older adults (college students tended to notice the change), Simons and Levin hypothesized that the older persons may have encoded the initial (young) experimenters simply as “college students,” whereas the college students may have encoded their peers at a more specific level. To test this hypothesis, the experimenters repeated the study, this time attired as construction workers. They reasoned that the college students might now encode them categorically as “construction workers” and, as a result, demonstrate greater change blindness. Indeed, now only 4 of 12 students noticed when a different construction worker emerged from behind the door to ask directions. Shallow encoding that does not go beyond a categorical level produces poor recollection of scene details and greater susceptibility to change blindness. In their review of research on change blindness,
Simons and Ambinder note how individual differences in expertise and culture (as well as age) can affect change-detection performance. For example, experts in American football are better able to detect meaningful changes in football scenes than those who are unfamiliar with the sport. Presumably, expertise guides attention when viewing images, thereby enhancing change detection for semantically meaningful changes.