Eye Tracking research

Application: driving

Gemma Briggs

What eye movements tell us…and what they don’t

They tell us…• areas of interest• number of fixations for a given time• scan patterns and hot spots, etc.They don’t tell us…• What information the viewer is extracting upon

fixation• What is happening in the brain whilst the person is

viewing a scene• If perception has occurred

Distraction and eye movements

• Increased cognitive workload leads to changes in visual scanning patterns.

• Tunnelled vision• Task demands can dictate visual

behaviour• Individuals may be unaware of such changes • People can look but not see (LBFS errors)

Driving research • How does visual behaviour

alter when dual tasking?• Do different types of

secondary tasks affect eye movements differently?

• What elements of the secondary task are most distracting?

• How do we allocate out attention?

• Can we learn to moderate behaviour?

Imagery experiment• View films from driver’s perspective. Some contained

hazards (central or peripheral), some didn’t. Participant had to react when they saw a hazard

• Half also completed a secondary, concurrent, imagery task via hands free telephone.

• Eye movements measured- scan patterns (position of hazard)- Variance of fixations in given time frame- Areas of interest• Reaction times for hazards• Number of hazards reacted to

Results

• Controls detected significantly more hazards than dual taskers (DT).

• For those hazards they detected, DTs took significantly longer to react than controls.

• For all central hazards, DTs took significantly longer to react than controls

• No sig difference in RTs between controls and DTs for peripheral hazards……but that’s because the DTs didn’t perceive them!

Results• DTs made significantly more LBFS errors than

controls

Control DT0

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1.5

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Condition

Mea

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LBFS

err

ors

mad

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Results

• Significant difference in variance of fixations between controls and DTs: controls increased eye movements when a central hazard was presented , DTs decreased their eye movements.

• Controls showed wider range of fixations. • DTs demonstrated visual tunnelling

Representative examples

Undistracted Dual tasking

Things to consider• You get a LOT of data from eye tracking!• Need a good sample size• Data collection can take a long time…but it’s

worth it• Need really clear research questions from the

outset• You won’t need a lot of the data you collect!• Think carefully about how you will analyse your

data• Be careful about the conclusions your draw

Thank you!