Response time synchronisation with stimulus on- and offset

[Paul Groot]

Since responses are asynchronous events, their recorded time-stamps
(RTTime) are not synchronized with the stimuli in any way. However, by
default, stimuli are synced with the vertical blanking interval of the
display, so the reported OnsetTimes will be synchronized. The response RTs
are simply the (asynchronous) response times relative to the (synchronous)
stimulus onset times: RTTime minus OnsetTime. So, RTs are not synced, but
the reference point (OnsetTime) is! If you look at RTTimes and RTs, you
should not see a correlation with the refresh interval.

As a side note: a lot of input devices use a polling scheme to detect
asynchronous button presses, or use communication protocols or software
that introduce systematic errors in the recorded response times. For
example, a keyboards might use hardware to scan the keys periodically. The
periodicity could be tens of milliseconds. However, these kinds of errors
are never synced with the refresh interval of the display.

Paul



On 12 March 2014 09:28, Aad Pors <aadpors at gmail.com> wrote:

> Does E-Prime synchronise the response time with the on- and offset of the
> stimuus (or with the screen refresh rate for that matter)?
>
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