latencies

Trial-by-trial variability in latency

Aim: Estimating the fixed and variable signal latency for the following:

- Psychopy stim computer
- Standalone EEGO system
- LSL triggers
- LSL recorder

Experiment 1 (variability in the recording of triggers, and fixed latency for the LSL trigger):

Design in Psychpy a for loop fixed 1sec delay. Repeat for 100 trials Recorder with EEGO the following sets:

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##     998    1000    1000    1000    1000    1000

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##     996    1000    1000    1000    1002    1002

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    6.00   12.00   12.00   12.16   14.00   16.00

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    6.00   12.00   12.00   12.16   14.00   16.00

B. Repeat with LSL recorder:

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   999.5   999.6   999.7   999.7   999.8  1000.6

Experiment 2:Send a trigger and produce a white screen for 1sec. Then a black screen for 4sec. Repeat for 100 trials.

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   14.00   30.00   34.00   34.32   40.00   44.00

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   14.00   29.50   34.00   32.96   36.00   44.00

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   38.00   45.50   48.00   49.02   52.00   60.00

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   44.00   50.00   54.00   53.82   58.00   64.00

Analysis

#effect of lsl triggers
hist(latencies_pd_eego_lsl-latencies_pd_eego_ttl)

mean(latencies_pd_eego_lsl-latencies_pd_eego_ttl)

## [1] 14.7

#effect of lsl recorder
hist(latencies_pd_lsl_lsl-latencies_pd_eego_lsl)

mean(latencies_pd_lsl_lsl-latencies_pd_eego_lsl)

## [1] 4.8

hist(latencies_pd_lsl_ttl-latencies_pd_eego_ttl)

mean(latencies_pd_lsl_ttl-latencies_pd_eego_ttl)

## [1] -1.36

#effect of lsl trigger under lsl recorder
hist(latencies_pd_lsl_lsl-latencies_pd_lsl_ttl)

mean(latencies_pd_lsl_lsl-latencies_pd_lsl_ttl)

## [1] 20.86