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Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059-1074. https://doi.org/10.1068/p281059
The scientific study of cognitive processes of attention and perception has been pioneered by subfields of cognitive psychology only in the previous few decades. The current experimental study by Simon and Chabris (1999) builds upon earlier evidences on two unique phenomena of ‘inattentional blindness’ and ‘change blindness’. In these two forms of cognitive blindness in perception of visual stimuli, people fail to notice parts of the visual stimuli or detect large changes in the objects or scenes when the environment is changed. Earlier research studies on these have led to the notion that we often perceive and remember only those details and objects which receive our focused attention.
Research studies in the past have explored the dynamics of perception and representation of the visual world and how attention plays a pivotal role. The current study attempted to improve upon shortcomings of previous experimental studies to provide a better idea on how the aspects of the visual stimuli and testing conditions contribute to inattentional and change blindness. Previous studies using visual search tasks (Mack et al., 1992; Mack & Rock, 1998) had participants expect certain target stimuli in their search using fixation points on screen and react accordingly. In other studies by Neisser and Becklen (1975), they used concepts from dichotic-listening tasks to present visual stimuli of two overlapping events to gauge perceptual blindness of one set of events while actively attending to the other. In subsequent divided-visual-attention tasks by Neisser (1979) and Becklen and Cervone (1983), they tested the effects of similarity of attended and ignored events, the time length of stimuli presentation and task difficulty on rates of inattentional blindness. The naturalistic properties of stimuli were also explored by latter studies (Stoffregen et al., 1989). In most of these studies, inattentional blindness was largely prevalent but with several issues in the nature of experiments or dissemination of study findings.
The current study by Simon and Chabris (1999) integrated the independent variables from a number of previous studies into a single design. This includes nature of unexpected stimuli (umbrella-woman, gorilla), style of video (superimposed, live), color of stimuli (black, white jerseys) and difficulty of task (easy, hard). There were four factors each with two levels in a 2X2X2X2 between subject design. There were a total of 16 testing conditions with 192 participants divided equally into each condition. The researchers’ objective was to examine the interaction between the various aspects of the experiment and they found that 46 percent of overall participants failed to notice the unexpected event, which was equivalent to previous studies. Participants noticed the unexpected event more in the easy condition and with the opaque display as expected. But surprisingly, the umbrella-woman stimulus was noticed more than the gorilla, which was assumed to be more visually salient. Similarly, unexpected event visually similar to the event was also noticed more defying earlier evidence of the opposite. The spatial arrangement of stimuli and timeframe of presentation were not found to be significant.
The study confirmed most findings from earlier studies regarding nature of attention and concluded that change and inattentional blindness are distinct characteristics of the visual system in most aspects of visual processing. It reiterated the notion that people fail to perceive any stimuli that is not given attention and they provided evidence for the same across various conditions. However, given the large number of testing conditions, the sample size in each condition was low and overall effect and power of the data analyses was low and limited to frequency counts. Nonetheless, the study was a remarkable effort in integrating scientific inquiries from decades on change and inattentional blindness.
References
Becklen, R., & Cervone, D. (1983). Selective looking and the noticing of unexpected events. Memory & Cognition, 11, 601-608. https://doi.org/10.3758/BF03198284
Mack, A., & Rock, I. (1998). Inattentional blindness: Perception without attention. Visual Attention, 8(01). https://psycnet.apa.org/record/1999-02040-003
Mack, A., Tang, B., Tuma, R., Kahn, S., & Rock, I. (1992). Perceptual organization and attention. Cognitive Psychology, 24(4), 475-501. https://doi.org/10.1016/0010-0285(92)90016-U
Neisser, U. (1979). The control of information pickup in selective looking. In Perception and its Development (pp. 201-219). Psychology Press. eBook: ISBN9781315787114
Neisser, U., & Becklen, R. (1975). Selective looking: Attending to visually specified events. Cognitive Psychology, 7(4), 480-494. https://doi.org/10.1016/0010-0285(75)90019-5
Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28(9), 1059-1074. https://doi.org/10.1068/p281059
Stoffregen, T. A., & Becklen, R. C. (1989). Dual attention to dynamically structured naturalistic events. Perceptual and Motor Skills, 69(3-2), 1187-1201. https://doi.org/10.1177/00315125890693-222
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