1. Procedure Baseline participants completed the category fluency task without seeing the video clip. Results Visual Acuity Young adults had better visual acuity (M Snellen denominator = 21.5) than older adults (M Snellen denominator = 28.7), t(55) = -5.30, p <.001. Accuracy in Counting Passes We calculated the absolute difference between the correct number of passes in the video (17), and the participant’s count. Data from one older adult was excluded for reporting a count more than 3 SDs from the mean for his age group. Young adults were marginally more accurate than older adults (M passes = 0.90 and 1.69, respectively), t(55) = -1.86, p =.07. No significant relationship between counting accuracy on the primary task and awareness of gorilla. Awareness of Irrelevant Stimulus Category Fluency Task Video participants were marginally more likely to generate one of the target words, “gorilla” or “ape” than baseline, χ 2 (1, N = 148) = 3.63, p =.06. This difference was primarily driven by aware young adults generating target words at a higher rate than young baseline participants (63.2% versus 23.4%; χ 2 (1, n = 66) = 9.42, p =.002). Unaware young and older adults did not differ from baseline in likelihood of generation. Experiment 2 Method Participants 20 young (M = 19.5) and 35 older adults (M = 73.8) participated. Same criteria for visual acuity, native language, and MMSE score as those in Experiment 1. Materials Materials were identical to those used in Experiment 1. Procedure The procedure was identical to Experiment 1, except participants counted the passes made by the team wearing black shirts. Results Visual Acuity Young adults had better visual acuity (M Snellen denominator = 22.8) than older adults (M Snellen denominator = 28.1), t(53) = -3.19, p =.002. Accuracy in Counting Passes Absolute difference between the correct number of passes (25) and the participant’s count, was smaller for young (M = 1.15 passes) than older adults (M = 4.43 passes), t(53) = -4.68, p <.001). No significant relationship between counting accuracy and awareness of gorilla. Absolute difference increased with higher Snellen scores for young, r(20) =.58, p =.008, and older adults, r(35) =.34, p =.04. The ability of unexpected events to capture attention is an important component of theories of attention, and of everyday functioning. The theory that aging reduces the ability to inhibit irrelevant stimuli predicts that task irrelevant material should gain access to working memory more frequently in older adults (Hasher, Lustig, & Zacks, 2007). Consistent with this, several studies have demonstrated greater susceptibility to distraction in older than young adults during selective attention tasks (e.g., Connelly, Hasher, & Zacks, 1991). These studies inferred capture of attention by irrelevant stimuli through measurement of performance on a primary task. An alternate approach is to measure awareness of the irrelevant stimuli directly, as is done in experiments of inattentional blindness. In the inattentional blindness paradigm, participants engage in a primary task, during which an unexpected and task-irrelevant stimulus is presented. The irrelevant stimulus may be presented briefly (Mack & Rock, 1998) or may remain visible for several seconds (Simons & Chabris, 1999). The surprising result from these studies is the large number of participants that fail to notice the irrelevant stimulus. Importantly, in all these studies the irrelevant stimuli are visible and noticed by all participants when not engaged in a primary task. The inattentional blindness paradigm offers a way to measure attention to a task-irrelevant stimulus directly by determining how often it is noticed. If older adults are less able to inhibit irrelevant information, they should be more likely to notice and report the irrelevant stimulus. We also examined implicit knowledge of the irrelevant stimulus in a category fluency task for the category “wild animals.” Experiment 1 Method Participants Experimental condition: 31 young (M = 19.1 years) and 27 older adults (M = 72.4 years). Baseline for implicit memory task: 47 young (M = 19.8) and 44 older adults (M = 71.9) Snellen visual acuity of 20/40 or better. Native English speakers. Older adults scored 27 or higher on the Mini-Mental State Exam. Materials 30 second video clip from Surprising Studies of Visual Awareness (Viscog Productions, 2003), in which six people are passing 2 basketballs (see Figure 1). Three of the people are wearing white shirts and pass one of the balls amongst themselves, while the other three are wearing black shirts and pass the second ball amongst themselves. Approximately halfway into the clip a seventh person, dressed in a gorilla costume, walks through the scene. The “gorilla” is visible on screen for approximately 10 seconds. Procedure Participants were instructed to watch the video and count the number of passes made by those wearing white shirts. After the video, the number of passes counted was recorded. Participants were given the category fluency task of writing as many examples of “wild animals” as possible in one minute. Participants were then asked if they had noticed anything unusual in the video. If they answered negatively, they were further asked if they had noticed a seventh person enter the scene. If they again answered negatively, they were shown the video a second time and instructed to watch without counting passes. Awareness of Irrelevant Stimulus Category Fluency Task Collapsing across age, video participants were not more likely to generate a target word than baseline. As in Experiment 1, young participants in the video condition were more likely to generate a target name than those in the baseline condition (50% and 23.4% respectively; χ 2 (1, N = 67) = 4.61, p =.03), but this difference was not significant for older adults (video = 25.7%; baseline = 34.1%). No significant difference in the likelihood of generating a target name for older participants who were unaware of the gorilla (20%), aware of the gorilla (30%), or in the baseline condition (34%; χ 2 (2, N = 79) =.105). Conclusions The inhibitory deficit model posits that with age, adults become less efficient at suppressing task-irrelevant information and preventing it from gaining access to working memory (Hasher et al., 2007). It has also been suggested that the phenomenon of inattentional blindness (Mack & Rock, 1998) is the product of inhibitory mechanisms functioning to deny irrelevant information access to working memory (Hasher et al.). Combining these two viewpoints leads to the prediction that older adults should be less susceptible to inattentional blindness than young adults because they are more likely to allow irrelevant information (i.e. the gorilla) to enter working memory. This prediction is clearly not supported by the current data. Rather, older adults are more likely to exclude the irrelevant and unexpected stimulus from attention than young adults. In contrast to previous work done by Mack and Rock (1998), the paradigm used in this study employed an irrelevant stimulus that was large, visible for several seconds, and passed through the participants’ visual field while engaged in the primary task. This paradigm, combined with the absence of a relationship between visual acuity and awareness of the irrelevant stimulus, suggests that it is not simply the poorer visual acuity of older adults that makes them more susceptible to inattentional blindness. The results from the category fluency task provide no evidence that the gorilla affected implicit memory in unaware participants, suggesting that it had not been processed at a lexical or semantic level. Although young aware participants produced the target words above baseline levels, this may have reflected explicit memory processes. References Connelly, S. L., Hasher, L., & Zacks, R. T. (1991). Age and reading: The impact of distraction. Psychology and Aging, 6, 533-541. Hasher, L., Lustig, C., & Zacks, R. T. (2007). Inhibitory mechanisms and the control of attention. In A. Conway, C. Jarrold, M. Kane, A. Miyake, & J. Towse (Eds.), Variation in working memory. New York: Oxford University Press. Mack, A & Rock, I. (1998). Inattentional blindness. Cambridge, MA: MIT Press. Simons, D. J. & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059- 1074. Viscog Productions, Inc. (2003). Surprising studies of visual awareness, volume 1 (DVD). Champaign, IL: Viscog Productions. Inattentional Blindness: Older Adults Are Superior to Young Adults in Ignoring Task-Irrelevant Information Elizabeth R. Graham 1,2, Diego Esparza-Duran 1, and Deborah M. Burke 1 1 Pomona College 2 Claremont Graduate University Figure 1. Still image of video clip from Simons and Chabris (1999). Figure provided by Daniel Simons. 61.3% of young and 11.5% of older participants reported awareness of the gorilla ( χ 2 (1, N = 57) = 14.77, p <.001; see Figure 2). Awareness was not related to Snellen score for either age group (both r pb s <.29) Figure 2. Awareness of task- irrelevant stimulus in Experiment 1. 100% of young adults and 57.1% of older adults reported awareness of the gorilla, χ 2 (1, N = 55) = 11.79, p =.001; see Figure 3). Awareness was not related to Snellen score for either age group (r pb s <.11). Compared with Experiment 1, both young and older adults in Experiment 2 were more likely to detect the gorilla when instructed to attend to the players wearing black shirts (for young, χ 2 (1, n = 51) = 10.12, p =.001; for older, χ 2 (1, n = 61) = 13.21, p <.001). Figure 3. Awareness of task- irrelevant stimulus in Experiment 2.