User`s guide

E-Prime User’s Guide
Appendix A: Timing Test Results
Page A-15
ABSOLUTE TIMING ERROR BY VARYING INTERVAL
Varying Interval (ms)
+1 +2 +3 PRIMES Grand Total
Average of ABS ERROR
0.174 0.166 0.155 0.121 0.162
StdDev of ABS ERROR
0.204 0.167 0.159 0.023 0.171
Min of ABS ERROR
0.026 0.051 0.032 0.057 0.026
Max of ABS ERROR
1.514 1.492 1.230 0.164 1.514
N (Num of Intervals)
100 100 100 25 325
2c. Refresh Rate Test – This test verifies that the ES can reliably detect and sync to the video
vertical retrace signal to get the exact number of refreshes requested by the experiment. In the
sample test below, the ES displayed stimuli while a photo-diode optical sensor detected each
display. The photo-diode then signaled the TS upon detection of a retrace, and the TS timed the
period between each signal (i.e., the refresh duration).
ABSOLUTE ERROR IN REFRESH DURATION
(ms)
Average of ABS ERROR
0.157
StdDev of ABS ERROR
0.292
Min of ABS ERROR
0.000
Max of ABS ERROR
1.937
N (Num of Intervals)
5000
3a. Key Response Test – This test creates a simulated subject response on the keyboard. The
TS computer plays the role of a subject as well as that of a recording device. The TS computer
monitors the display with a photo-diode sensor. When it detects a stimulus, it delays a preset
duration and then toggles a bit which activates a reed relay. This, in turn, activates a modified
keyboard as if a subject had pressed a key. This test is run via both single frame and multi-frame
stimulus presentations in E-Prime (e.g., a single Probe collecting a response vs. a presentation
sequence of Probe1, Mask1, Probe2, Mask2 that is collecting a response running over the entire
sequence). The sample data below shows that the keyboard produced a fairly constant delay
averaging about 6.6ms with a standard deviation of <0.85ms. Considering that normal human
response times generally have a standard deviation of over 100ms, the added variability is
negligible. Also, since the delay is likely to be equal across all conditions and is represented in
the base reaction time, it is unlikely to influence experimental results.
ACTUAL KEYBOARD RESPONSE DELAY BY FIXED INTERVAL (SINGLE FRAME)
Fixed Interval (ms)
1 100 10000 Grand Total
Average of ACTUAL DELAY
6.576 6.364 7.705 6.476
StdDev of ACTUAL DELAY
0.792 0.792 1.103 0.805
Min of ACTUAL DELAY
4.802 4.802 5.808 4.802
Max of ACTUAL DELAY
8.804 8.804 9.816 9.816
N (Num of Intervals)
1000 1000 10 2010