Last week I had a gorilla introduce you to "inattentional blindness". Such blindness arises when the mind focuses on a task. That focus means that attention is withdrawn from the rest of the environment. In the case of my example, respondents were asked to focus on counting the number of passes in a basketball game. In particular they were asked to count passes between the team dressed in white. So engrossing was the task that the respondents did not see a “gorilla” walking across the court. (An accomplice dressed in a gorilla outfit). It turns out that I was suffering from the same effect. I was too focused on my theme of System 1 and System 2 thinking. I failed to notice that the academic literature was awash with gorillas!

“The invisible gorilla strikes again” is a replication of that first study. In this case the task was much more realistic. Radiologists were screening lung scans for cancer. They were looking for nodules. To one of the scans was added a silhouette of a gorilla. It was forty eight times the size of a typical nodule. 83% of the radiologists did not notice the gorilla. They were so engrossed in looking for nodules.

Other replications of the study found two interesting insights. The first is that the presence of the gorilla altered the accuracy of the count. Even though the gorilla was not always consciously registered, the resultant “pass count” was less accurate. It did distract enough in every case to reduce the accuracy. The second finding was that it mattered whether respondents were asked to count passes by the white or the black team. The gorilla was noticed more often by those people who were asked to count the passes by the team wearing the black tee shirts. The gorilla outfit was also black. The researchers’ conclusion was that this triggered the observation.

In the “ Gorillas we have missed” study the authors extended the idea to hearing. They created a sound play. This was a realistic stereophonic recording to be listened to on headphones. In one side of the scene there were two women chatting to each other and packing a parcel for a party. In the same room were two men having a separate conversation. They were talking about the food and drink for the party. Respondents were asked to listen to either the men or the women. Into the “play” was introduced a separate male character. He walking across the sound stage for 19 seconds saying “ I am a gorilla”. The effect was the same. If asked to listen to the women a significant proportion of the respondents dig not hear the “I am a gorilla”. If asked to listen to the men the effect was the same but the incidence of spotting the intruder was higher.

All our senses seem to be sensitive to this effect. Other researchers set up two visual computer based tasks. Both involved finding hidden letters. One required significantly more “mental effort”. Respondents were brought into a room full of the smell of freshly roasted coffee beans. Respondents first completed one of the letter finding tasks. They were then asked about their perceptions of the laboratory. They were prompted generally about the environment. Then they were asked specifically about a coffee smell. Like the gorilla, the coffee smell disappeared depending on the amount of mental effort required by the task. The same study repeated by other researchers showed that our sense of touch could be supressed. Fingers became numb to a roughened surface when focusing on a difficult task.

“Aging Increases Inattentional Blindness to the Gorilla”

The paper with this title looked at the impact of ageing on this phenomenon. Researchers on ageing have two rival hypotheses in this area. The first is that as we age we lose the ability to regulate attention. We are less able to focus on a task and are more subject to distraction. The alternative theory is that we have a fixed capacity of attention which is reduced with age. If we allocate to much to a given task there is less available for other tasks.

They repeated the basketball game and the gorilla study with a young and an old sample. The results showed that the older group did a lot worse. When asked to count passes by the team in the white tee shirts they only spotted the presence of the gorilla in 10% of cases. The group of 17-22 year olds spotted the gorilla in 60% of cases. They still missed a lot. When focused on counting the passes between the team dressed in black, the 61-81 group spotted the gorilla 55% of the time. The young group was 100%.

The researchers thus cast doubt on the idea that age brings with it the loss of our ability to inhibit distraction. This has been a long standing part of the ageing stereotype. If that was the case we would be more distracted from the counting task and see the gorilla more often. It seems more likely that with age the pool of “attention” we have shrinks. If we focus on one task there may not be enough left over to do other things. Given the increased need for perceptual completion, as one or possibly two senses fade, this may be draining the attention pool.

Day to Day life.

If we are more likely to miss a gorilla in basketball game what does it say about an older person driving? They are correct to self-regulate and avoid poor visibility. They should avoid other tasks whilst driving. If they get lost they should stop to re-orientate themselves. They should not try to do it whilst still driving.

Watching television whilst eating may not be such a good idea. Eating is a social phenomenon. We like to eat with others and eating alone is a source of depression in older people. A study in Japan found that 24% of older people were eating the majority of their meals alone. A television can provide company but it will also draw from that pool of attention. Does it matter? There is a lot of evidence that watching television whilst eating is bad for our nutrition. We care less about what we are eating.

There is also quiet a lot of evidence that we eat most of our meals on “autopilot”. We have a set of expectations for what the meal will look and sound like. We anticipate what it will smell and taste like and the touch of the food in our mouths. If the meal confirms with those expectations we do not consciously register any of it. Only if something is unusual do we re-engage System 2 to review the meal. Our nutritional habits will therefore be fixed by a life time of meals not one TV Dinner!