Stroop task

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Screen shot of PEBL's Stroop Test
Screen shot of PEBL's Stroop Test


[edit] About

Two versions of the Stroop test are available in PEBL. The Stroop test is a classic test of attentional filtering. It is typically demonstrated as a reading versus color naming task, where reading is more automatic and thus less impacted.

[edit] Notes

Located in battery/stroop/stroop.pbl and battery/stroop/vstroop.pbl

The standard PEBL stroop test compares color naming versus word naming under three response conditions (impacting what the screen looks like). These are specified in colorresp in the output data, and are:

0: black color names 1: in-color color names 3: color patches (no text)

Results typically produce interference opposite to what naming does, because it is easy to match the color shade between the stimulus and response, but hard to actually read the color, which is now interfered with.

[edit] Options

   ##The number of trials per block (and condition)
   blocklength <- 50

[edit] Data Output

For the standard stroop test, data are output in a file stroop-<gsubnum>.txt, with the following columns:

sub is the subject code entered at startup
block is the block number (different response types)
trial is the trial number 
type is block type (1= response by name, 2= response by shade)

colorresp is whether the response targets are labeled in color:
          0 is black text, 
          1 is in-color text
          3 is just shade (no text)
cond is the stimulus condition 1-4:
    1. color name and color match.
     2. color name does not match color.
     3. color name normal; color is black
     4. color name is 'xxxxx'; color is normal

 cond2 is a 3-level translation of cond.  No block contains
    both conditions 3 and 4, so these are mapped into the same 
    single-feature condition called 3.  (1->1, 2->2, 3->3, 4->3)

shade is the name of the stimulus's color 
wordname is the stimulus word 
resp is the actual response (1-4) made
corr is whether it is correct 
respnum is a counter regarding how many times they responded to the stimulus (they may
 have taken multiple errors before getting it right). 
 startTIME is the absolute time (in ms) of the start of trial rt is the time (in ms) of the response
Note that every trial must be finished "correctly", which means if you make an error, the data line Can get logged every time until you get it right.

Basic response times and accuracies are also given for each condition in the file stroop-summary-X.txt.

Typical results from PEBL's Stroop Test

[edit] References

Troyer, A. K., Leach, L., & Strauss, E. (2006). Aging and Response Inhibition: Normative Data for the Victoria Stroop Test. Aging, Neuropsychology & Cognition, 13(1), 20–35. doi:10.1080/138255890968187

[edit] See Also

PEBL Test Battery

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