We live in a world that is loaded with more information than we can process. Attention helps us filter out that which is less significant to attend to that which is necessary or expedient. We can take in 30 to 40 images per second in sweeping glance, but our brain can't possibly pay attention to all of them. We only have the ability to retain a few of them, so we (or our brains) select what is significant to us. Sometimes, the objects in our visual field call for attention, but this differs from the manner in which we see by selection.
We tend to notice changes from the norm, but we also tend to miss big ones from time to time. As we noted in The Invisible Gorilla experiment, factors can compete for and divide our attention. Oddly enough, however, though we are very attuned to small changes, we research indicates that we can tend to miss the large ones.
According to research, both environmental and emotional factors divert our attention and affect what we are able to notice or retain. Rapid blinking, eye movement, the flickering of light, or intermittent introduction of something that partially occludes the visual field (“masking”) significantly diminishes a person's ability to pay attention – and those factors don't have to be very dramatic. In a study where people were shown a projected picture with notable changes which were separated (interrupted) by a blank screen, they were much less likely to recall changes between the first and second images. There's also a study wherein investigators switched out strangers with whom the test subjects were conversing during a significant attention-breaking interval. Many people never noticed, even though we human beings show a tendency to prefer faces.
Another study involved showing photographs of certain scenes to participants in advance of viewing a film. Nearly 80% believed that they could identify the scenes, but people's abilities fell fall short of their predictions. Interaction with others enhances the detection of change – when subjects are put into teams, everyone's overall performance improves.
Age, attentiveness, health, and medications also change the ability to take in information.
Another reason why we may experience change-blindness stems from our past experience. We learn to observe subtle cues (with scent being a major factor) which herald gradual changes which give us hints that change is coming. But life is dynamic, and this belief that we can sense change approaching lulls us into a false sense of confidence about our awareness. (We human beings aren't as good as we think we are.)
The nature of a person's training and practiced skill also affects what a person notices in their visual field. Familiarity with the scene or aspects of it enhance the amount of visual input that the mind can notice. There is less completely new data to process, and the mind transfers that skill over into the new situation.
Filling in the Gaps
As mentioned before, our expectations transfer to the things to which we pay attention, affecting what we see. If we have a vested interest in avoiding change, we may subconsciously ignore those indicators. We tend to construct a narrative around what we see and plug those images into it. That overlaps into other cognitive biases that interplay with tagging visual images with meaning. When we don't know it, we make it up.
For Further Reading until the next post:
- One of the $3 Kindle books about Cognitive Bias at Amazon.com
- Chabris & Simons' The Invisible Gorilla
- Levin Lab's articles (in pdf)
- Gilovich, Griffin & Kahneman's Heuristics and Biases
- Robert Cialdini's Influence: The Psychology of Persuasion
- Judith Herman's Trauma