National Brain Mapping Lab

Psychophysics

Psychophysics is a branch of science that quantitatively investigates the relationships between the stimuli and our sensory systems.

These stimuli must be objectively measured; an example of this is the variation of lights in terms of luminance. Vision, hearing, taste, smell, touch and time have been constantly studied by psychophysicists.

The field of psychophysics was pioneered by Gustav Fechner in the 1860s. Fechner introduced various methods for quantitatively measuring the relationship between stimuli and perception. From his studies, Fechner developed a logarithmic scale that is commonly used today and is called the Fechner scale.

Facilities (Top)

Tobii Pro Glasses 2 Eye Tracker (Top)

Tobii Pro Glasses 2 Eye Tracker

Eye tracking Tobii Pro Glasses 2
Gaze sampling frequency 50 or 100 Hz
Calibration procedure One point
Calibration validation Yes
Parallax compensation Automatic
Slippage compensation Yes, 3D eye model
Tracking technique Corneal reflection, binocular, dark pupil tracking
Pupil measurement Yes, absolute measure

Tobii TX300 eye tracker unit (Top)

Tobii TX300 eye tracker unit

Specification of Tobii TX300 eye tracker unit  
Sampling rate (binocular) 300 Hz *
Sampling rate variability <0.3%
Processing latency 1.0-3.3 ms
Total system latency <10ms

1- Eye tracking studies (Top)

For eye tracking studies, our lab uses the Tobii Pro Glasses 2 (The system captures data at 50 or 100 Hz) and Tobii Pro TX300 Eye Tracker (collects gaze data at 300 Hz yet allows large head movements). To run the tracking application, we use a PC with a 3.20 GHz Intel Core i5 CPU and 8GB of RAM.

2- Non-Eye tracking studies (Top)

For non-eye tracking studies, data collection is performed by running the experiments on 3 PC with a 3.20 GHz Intel Core i5 CPU and 8GB of RAM.

3- Software Systems (Top)

We use the following software systems in our lab for research and experimental studies:

  • Matlab
  • psychtoolbox
  • Psychopy
  • Java
  • SPSS

List of Services (Top)

Eye tracking (Top)

One way we measure people's behavior is recording their eye movements. Where people look and how they move their eyes can inform us about how people think. Usually eye tracking is used on participants as they perform some behavioral task. For decrees the movement of head in an eye tracking experiment use the chin rest.

Behavioral experiments (Top)

In a typical behavioral experiment, participants sit in front of a computer screen and they are presented with visual or auditory stimuli, or sometimes both at the same time. Participants would be required to respond to the stimuli usually by pressing computer keys as instructed by the experimenter.