OS = Win10
PsychoPy version 1.84.1 (BUILDER)
Frame rate 60Hz
What are you trying to achieve?
Hi, I am running simple lexical decision tasks and therefore interested in Reaction Times (RTs).
However, the data output shows that the reaction times have been rounded to the nearest frame (i.e., they are roughly multiples of 16ms). For example, several responses are 434ms, and several are 451ms, several are 467ms, with nothing in between. I’ve attached an excel file (1st sheet shows RTs; 2nd sheet shows the LOG) sorted by RTs to illustrate this.LexDecRT.xlsx (143.1 KB)
I have difficulty understanding why (since ultimately, RTs should be dependent on keyboard press rather than frame rate). It’s particularly worrying because I expect only small priming effects of 30ms in the experiment (which would be diluted by what I’ve described above)
What did you try to make it work?:
I’ve checked other timing properties of the experiment and they seem to be fine: the log file shows that the stimuli is being presented as it should be (e.g., a prime word appears for 4 frames/66.667ms, and is immediately followed by the target word).
I’ve also tried checking and unchecking ‘Sync RT to screen’, using different stimuli, using different PCs, etc. I have been using Psychopy builder for a week now and really do feel like I’ve read every (builder) demo and manual-page that I can, so would appreciate any suggestions about why this occurs, and if it can be fixed?
What specifically went wrong when you tried that?:
Reaction times were still rounded to the nearest frame (i.e., multiples of 16.666ms) (as outlined above). Thank you for your time.