Posts Tagged ‘traffic signs’

So Then, How Good is the Human Visual System?

July 14, 2019

The simplest way to answer this question is to ask how frequently is the human visual system relied upon. Stefan Van Der Stigchel writes in his book “How Attention Works: Finding Your Way in a World Full of Distraction,” “When it comes to the transfer of information, the visual system is our single most important sensory tool. It takes a lot longer to convey the same information orally through speech than visually with the aid of symbols. This is because the visual system is able to process information in the blink of an eye. If you show someone a very detailed photo for just a second or two, they will still be able to describe the image to you fairly accurately afterward.”

In the 1970s Mary Potter conducted a series of experiments that clearly demonstrated this ability to rapidly process visual information. Research participants were given a written description of a scene (for example, “traffic on a street”) and then asked to find that scene among a series of images presented to them in quick succession. They were instructed to press a button as soon as they had identified the scene that identified the written description. No visual information regarding the scene was provided, neither the color of the cars nor the layout of the street. When the presentation rate was eight scenes per second, there was a success rate of 60% when it came to finding the scene that had been described in writing. This means that each image was visible for just 125 milliseconds, and the participants had to process all of the visual information in each scene within this extremely short space of time. A second study in which the participants only had to describe which scenes they had seen after the event only 11% of them were able to describe the scenes in any detail. Although they could say which scenes they had been shown, they were unable to provide any specific information about the content.

The difference in the results of these studies reveals distinct stages of information processing. All of the visual information that falls on the retina is registered in the brain. This information includes the colors and shapes of the world around us, and is processed in the primary visual cortex. At this stage we are still unable to identify individual objects. “Seeing” describes everything that falls as light on the retina. Although we “see” a lot of stuff, we only process a small amount of information deeply enough to know what that stuff actually is. Identification, knowing whether something is a tree or a green building, requires more in-depth processing and access to the identity of the object.

If we want to communicate a visual message, such as the information in a traffic sign, it is important to know what kind of information we can communicate in an instant. Although visual information can be communicated very quickly, there are limits. We are unable to process full sentences in a blink of an eye. Symbols, assuming the meaning of the symbol is known, are much more effective in this respect. Of course, it is impossible to devise a symbol for every piece of information, but when a road has multiple complicated signs, it can be to the detriment of both the message being communicated, and the intended recipients of the information, that is, the road users.

The communication of information is regarded as being successful when the relevant information reaches the intended user. Regardless of how impressed we might be by a particular advertisement, if we do not remember the intended message after being the advert (the name of the product), then the advertisement will not have worked and the attention architect will have failed in his or her task. HM remembers many advertisements, yet being unable to remember the name of the product. Perhaps HM has suffered brain damage, and is an atypical subject. Yet he is able to write a blog, so readers can reserve judgment. There are other advertisements, which he remembers but dislikes and is not prone to purchase the product. HM would very much like to review research on advertisements and how their effectiveness is evaluated.

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