Lecture 8A: Physiological Measures Flashcards
What kind of evidence does eye tracking provide about a user’s visual processes?
objective and quantitative evidence
What can’t eye tracking be impacted by?
subjective thoughts
What is the eye-mind hypothesis?
where participants are looking indicates what they are processing
How does eye tracking work?
Near IR light shines onto the cornea which reflects back to and is tracked by the IR camera
What are the two types of eye tracking?
screen based (stationary)
eye tracking glasses (head mounted)
What are fixations?
spatially stable glazes during which visual processing occurs; characterized by location and duration
What is the range for the duration of a fixation?
100-300ms
What is a saccade?
the rapid eye movements in between successive fixations
What is a scan path?
sequence of fixations and saccades
What is the area of interest?
regions of the display on which analysis is conducted, generally defined by the experimenter
What is gaze/dwell?
series of fixations within a particular area of interest, beginning with the first fixation on that AOI and ending with the last fixation inside of that AOI
What does a large total fixation number mean?
indicates additional or unnecessary information that’s being processed the larger the number gets
What does a high value mean fixation duration represent?
high amount of clutter, difficulty extracting information; could also mean that people are interested in the targets
What is the scan path length?
the total length of the scan path from the first to the last fixation; shorter scan paths indicate a more efficient search
How does pupil size correlate to workload?
pupil size increases with increasing workload/task demands
What is the blink rate?
number of blinks per second
Besides scan paths, what’s another way to visualize eye tracking? what is it’s limitation?
heat map; doesn’t give sequence information
What are three problems with eye tracking?
cannot track peripheral vision
debate about eye mind hypothesis
shows where but not why
What is PPG (photoplethysmography)
heart rate monitor that uses a light source to measure variations in reflected light intensity associated with pulses
What is ECG (electrocardiography)?
heart rate monitor that measures the electrical activity of the heart
What is heart rate?
number of heart beats per minute
What is heart rate variability?
fluctuation in the time intervals between adjacent heartbeats
How is heart rate correlated to workload?
higher HR and shorter R-R (lower HRV) under high cognitive workload
What is galvanic skin response (GSR) or skin conductance response?
an objective transient indication of autonomic nervous system arousal in response to a stimulus
