Beauchamp:Perceptual Biasing

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Brain picture
Beauchamp Lab


Perceptual Biasing
1. Select "HumanBiasPerception" from available KNOT plugins.
2. On toolbar, open Channel Settings, Stimulus Settings and Behavior Settings windows.
3. Enter the names of all Channels.
4. Check to see that the following fields in Stimulus Settings have default values specified below:

a. Pre-Interval (ms): 250 (period before Interval One)
b. Interval (ms): 300 (length of each interval)
c. Inter-interval (ms): 1000 (period between Interval One and Interval Two)
d. Post-interval (ms): 50 (period after Interval Two)
Note that there is only one interval in this plugin. For now, presentation of the visual stimulus is time-locked to the electrical stimulation Interval defined by the parameters above.
e. Select "Images"
i. Images Stimuli: 7
ii. Azimuth (deg): 0
iii. Elevation (deg): 0
Note that "Images Stimuli Loaded" is a counter for the number of Images Stimuli that have been loaded so far. You can press the main Reset button, which will not reset the images loaded but will reset the eStimData window with all data plots. The "Images Reset" button, on the other hand, resets everything, including the images loaded.
v. Size (deg): 25
vi. Press "Load Stimulus Images" and select all images in Desktop/Organized Images/BiasPerception as default. The images in this directory should be unique to every electrode and the result of selectivity screening. Stimuli will include a spectrum of ambiguity between a strongly preferred and anti-preferred stimulus.
f. Select "Electrical"
i. Currents: 3
ii. Indicate Max. Current (uA) from Microstim Staircase detection threshold data.
iii. Indicate Steps per Octave from Microstim Staircase detection threshold data. Current Factor will scale automatically.
iv. Frequency (Hz): 200
v. Pulse Width (uS): 200
v. Indicate "uA per V output" (If range max is below 1000 uA, use 100 uA per V. If range max is above 1000 uA, use 1000 uA per V.)
vi. DA Channel Out: 0
vii. Marker Pulses Bit: 1
viii. Gate Bit: 0
ix. Check "TTL Marker Pulses."
x. Check "TTL Gate."

Note that subject will be making a judgement between preferred (2) and non-preferred (1) in a discrimination task.

Back to Setup Apparatus.

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