Christopher Chabris and Daniel Simons constructed a short film (link) of two teams passing basketballs, one team wearing white shirts, the other wearing black. The viewers of the film are instructed to count the number of passes made by the white team, ignoring the black players. This task is difficult and completely absorbing. I highly recommend performing the exercise described above to get the maximum effect.
Many thousands of people have seen the video, and about half of them do not notice anything unusual. Spoiler alert – the unusual event is described at the end.
In the realm of investigative interviewing, the reliability of witness testimony is often taken for granted. However, psychological research reveals critical insights into human perception and attention that profoundly impact the way interviews should be conducted.
The experiment using the video highlighted two fundamental principles about human cognition:
· People can be blind to the obvious. Even a striking, unexpected event can go unnoticed if attention is focused elsewhere.
· People are blind to their own blindness. Those who missed an event can be adamant nothing occurred, underscoring a lack of awareness about their own limitations.
The findings of this study have profound implications for investigative interviewing, particularly in witness accounts of crimes or incidents. Traditional interview techniques often assume that a witness sees and remembers all relevant details. However, the principles of in-attentional blindness suggest that even crucial events may go unnoticed if the witness's attention was focused elsewhere.
A witness may be highly focused on one aspect of an event—such as the face of an assailant or the sound of a gunshot—while missing other critical details, like the presence of a second perpetrator or an object in their surroundings. Interviewers must recognize that attention is selective and that gaps in a witness's account do not necessarily mean deception or untruthfulness.
If a witness is blind to certain elements of an event, they may be susceptible to suggestibility. Leading questions can implant false memories or distort existing ones. For example, if an interviewer asks, "Did you see the red car speed away?" The witness, despite not noticing a red car, may later "remember" it simply because of the question’s framing. To mitigate this, interviewers should employ open-ended questions, such as, “describe everything you saw?"
The Cognitive Interview (CI) technique, based on psychological principles, can help overcome some limitations of inattentional blindness. CI encourages witnesses to:
· Reconstruct the context mentally, which can enhance recall.
· Change perspectives, as describing the event from another viewpoint may reveal overlooked details.
· Report everything, no matter how seemingly insignificant, as minor details can be pieced together to form a clearer picture.
Just as witnesses may be blind to the obvious, investigators can be blind to their own cognitive biases. (Confirmation bias - the tendency to favor information that aligns with preexisting beliefs) can lead interviewers to unconsciously dismiss or downplay details that do not fit their expectations. Recognizing and actively countering this bias is crucial for objective interviewing.
Seeing the Gorilla in Investigative Interviewing
It is the counting task - and especially the instruction to ignore one of the teams that causes blindness. No one who watches the video without that task would miss the unusual event. In the video about halfway through, a person wearing a gorilla suit appears, crosses the court, thumps their chest, and moves on. The gorilla is in view for 9 seconds. Many thousands of people have seen the video, and about half of them do not notice anything unusual. The "Invisible Gorilla" study serves as a crucial reminder that perception is not as reliable as we often assume. Investigative interviewers must account for inattentional blindness and cognitive limitations when assessing witness testimony.
Don’t miss the gorilla in the training field!
