Simon and Chabris (1999)

Question 1

Background

Answer 1

Change blindness is where individuals often do not detect large changes to objects and scenes from one view to the next.

Inattentional blindness occurs when attention is diverted to another object or task and observers often fail to perceive an unexpected object, even if it occurs at the point of fixation.

Question 2

Aim

Answer 2

To build on previous research into divided visual attention and to investigate inattentional blindness for complex objects and events in dynamic scenes.

Question 3

Procedure

Answer 3

Primarily a laboratory experiment that used an independent measures design.

The independent variables (IVs) were whether the participant took part in:

1. The Transparent/Umbrella Woman condition
2. The Transparent/Gorilla condition
3. The Opaque/Umbrella Woman condition
4. The Opaque Gorilla condition.

For each of the four displays there were four task conditions:

1. White/Easy
2. White/Hard
3. Black/Easy
4. Black/Hard.

Overall there were therefore 16 individual conditions.

The dependent variable (DV) was the number of participants in each of the 16 conditions who noticed the unexpected event (Umbrella Woman or Gorilla).

4 videotapes, each 75 seconds in duration were created.

Each tape showed two teams of three players, one team wearing white shirts, the other black shirts.

The members of each team passed a standard orange basketball to one another in a standardised order.
After 44-48 seconds of action, either of two unexpected events occurred.

Question 4

Sample

Answer 4

228 participants, almost all undergraduate students.

Data from 36 patients discarded because they had heard about the study previously, so only 192 Ps results used.

Question 5

Data collection

Answer 5

After viewing the video tape and performing the monitoring task, participants were immediately asked to write down their count(s) on paper.

They were then asked the following additional questions:

1. While you were doing the counting, did you notice anything unusual in the video?
2. Did you notice anything other than the six players?
3. Did you see a gorilla/woman carrying an umbrella walk across the screen?

Question 6

Findings

Answer 6

1. Individuals have a sustained inattentional blindness for dynamic events, e.g. 46% of participants failed to notice the unexpected event.
2. The level of inattention blindness depends on the difficulty of the task, e.g. more Ps noticed the event in the Opaque condition than the Transparent condition and 64% noticed in the Easy condition compared to 45% in the Hard condition.
3. Individuals are more likely to notice unexpected events if they are visually similar to those they are paying attention to, e.g. the gorilla was noticed by 58% of the black team and only 27% of the white team.