EYE TRACKING TESTS FOR COGNITIVE IMPAIRMENTPriyanka Bhojwani

AGENDAWhat is Cognitive Impairment?

What is Eye-Tracking?

Interpretation of Eye Tracking Data

The Relationship between Eye Tracking & Cognitive Processes

Indicators of Cognitive Impairment through Eye Tracking

Example of an Eye Tracking Test

Limitations

WHY SHOULD WE CARE?• Cognitive impairment is when a person has trouble remembering, learning

new things, concentrating, or making decisions that affect their everyday life.

• More than 16 million people in the United States are living with cognitive impairment

• Age is the greatest risk factor for cognitive impairment• Cognitive impairment is costly. People with cognitive impairment report

more than three times as many hospital stays as individuals who are hospitalized for some other condition

• Individuals may reduce the risk of cognitive impairment by keeping physically active and maintaining healthy cholesterol and blood sugar levels

WHAT IS EYE – TRACKING?• In the simplest terms, eye tracking is the measurement of eye activity• Eye tracking data is collected using either a remote or head-mounted

‘eye tracker’ connected to a computer• generally include two common components: a light source and a camera.

The light source (usually infrared) is directed toward the eye. The camera tracks the reflection of the light source along with visible ocular features such as the pupil.

• This data is used to extrapolate the rotation of the eye and ultimately the direction of gaze

INTERPRETATION OF EYE TRACKING DATA

Most Common Method: • analyze the visual path of one or more participants across an interface

such as a computer screen.• Each eye data observation is translated into a set of pixel coordinates.• From there, the presence or absence of eye data points in different screen

areas can be examined• This type of analysis is used to determine which features are seen, when

a particular feature captures attention, how quickly the eye moves, what content is overlooked and virtually any other gaze-related question

THE RELATION BETWEEN EYE TRACKING & COGNITIVE PROCESSES

• Eye movements in reading have long been a focus of research because of the regularity of fixation patterns and the tight link between fixations and comprehension (Rayner, 1998).

• The fixation patterns on a picture were fundamentally different when observers were trying to answer different questions about the picture (Yarbus,1967)

INDICATORS OF COGNITIVE IMPAIRMENT THROUGH EYE TRACKING

Some studies have been showing that patients with MCI: • Have difficulty processing color information (http

://www.ncbi.nlm.nih.gov/pubmed/10838150/)• Demonstrate slow pursuit movements (http

://www.ncbi.nlm.nih.gov/pubmed/3340292/)• Show reduced contrast sensitivity (http://www.ncbi.nlm.nih.gov/pubmed/15842071/)• Decreased reading speed (http://www.ncbi.nlm.nih.gov/pubmed/15842071/ )• Impaired face or object recognition

(http://www.ncbi.nlm.nih.gov/pubmed/17941352/) • Increased pupil dilation during a visual search, indicating increased effort

(http://www.ncbi.nlm.nih.gov/pubmed/19595301/ )

LIMITATIONS• Fixations do not reveal much more than that the observer attended to

these locations• Fixation duration is thought to correspond to cognitive processing ease or

difficulty but in scene perception research, out of context objects generate longer fixations

• The experimenter has little control of, and does not know, what the observer is doing, and consequently inferences are limited.

• Therefore a given cognitive event might reliably lead to a particular fixation, the fixation itself does not uniquely specify the cognitive event. (Viviani, 1990)

REFERENCES• Centers for Disease Control & Prevention. (2011). Cognitive Impairment: A Call for Action

Now! Centers for Disease Control & Prevention.

• Pereira, M. L., Camargo, M. v., Aprahamian, I., & Forlenza, O. V. (2014). Eye movement

analysis and cognitive processing: detecting indicators of conversion to Alzheimer’s disease.

Neuropsychiatric Disease & Treatment.

• Rayner, K. (1998). Eye Movements in Reading & Information Processing: 20 years of research.

Psychological Bulletin.

• Yarbus, A. L. (1967). Eye Movements During Perception of Complex Objects. In A. L. Yarbus,

Eye Movements & Vision (pp. 171-211). Springer.