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Action and Cognition Lab Tools

In the Action Lab we use a combination of different tools to investigate information processing as it unfolds in real time. The lab is currently equipped with an Optotrak Certus, which is an optical motion capture device that can track an individual's movements with sub-millimeter and sub-millisecond precision. We also have an Ultrasound system that can be used in conjuction with the Optotrak system to record the movements of the articulators that are otherwise out of view (e.g. the tongue). In addition, we have a 64-Channel BioSemi ActiveTwo EEG system and a Magstim Rapid2 Transcranial Magnetic Stimulator.

These systems allow our researchers to use participant action as a measure for various tasks. For example, instead of asking participants to respond by pressing a button or triggering a voicekey, we ask them to reach out and touch or grasp an object. By analyzing the kinematics of the participant's reaching response, we are able to compare several different dependent variables (e.g. peak velocity, peak acceleration, curvature and others) across different experimental conditions. Data analysis can be done using C-Motion's Visual3D, or with custom, in-house analysis programs.

Some recent equipment additions to our lab include a 3D monitor that can present stimuli that appear to come out of the screen. We use this in grasping research, in conjunction with a Cyberglove that records hand posture by measuring the joint angles of 23 joints in the hand. The lab also uses a Minibird to measure 3D position and orientation, and a Phantom-Haptic (force feedback) device that applies arbitrary forces to the person holding it, so that it feels as if you are interacting with a real object.

Optotrak Extension for Presentation

We have developed in-house an extension to Presentation to interface with the Optotrak Certus. Released under an open-source license we are making this tool available to interested researchers. All that we ask is that you register with us for the download.

The Lab in Action

An important feature of the lab is the real time interface between the Optotrak system and the stimulus-presentation system. This allows researchers to employ experimental designs whereby they can change the stimulus display depending upon the participant's movement position or velocity. It also allows for the use of psychophysical experiments in which stimulus properties vary during the course of an experiment as a function of various kinematic measures. You can see a demonstration of this real time interface in the video below. Note how the square on the screen changes location and size to reflect movements in 3D. Notice also that the colour of the square changes as the velocity of the movement changes.

Movement trajectories from a single subject in a masked congruence priming experiment in which the task was "Is it an animal or a tool?". In the "Congruent" condition, both the masked prime and the target referred to the same target (e.g. dog [prime] - DOLPHIN [target]). In the incongruent condition, the prime and target stimuli referred to opposite categories (e.g. hammer - DOLPHIN). The greater tendency by this subject to initially point to the wrong target in the incongruent condition suggests that the processing of the prime stimulus proceeds all the way down to include the formulation of an overt motor response.