MinMax - Setting RT Limits

QuickInfo

Defines the range of acceptable response times. RTs under the minimum or over the maximum cause a message screen to appear

Values

0 for none OR two integers separated by a dash (e.g.) 200-1500.

Details

In some case you may want to notify participants that they are responding too quickly or too slowly. If so, you can associate a MinMax value with the style you are using for that trial. If the RT is under the minimum or over the maximum the participant will be presented with screens that you define in Options.

If you do not want the feedback to occur as a function of response time, then you would normally use a MinMax value of 0 (e.g., in the case of instructions)

However, if you have some other reason to use a MinMax value other than for feedback (see below) and you don't want feedback displayed, then you can simply tell DirectRT to display the feedback for 0ms. To do this click Options while in the Style file and set the delay value for feedback to 0.

Advanced Options

Automatic Continuation

An exclamation mark (!) following the value in the MinMax field will cause DirectRT to automatically proceed when the maximum time allowed for the response is reached (e.g., 200-1500!). Otherwise, DirectRT will wait for the response defined in the Time column cell for that stimulus before delivering the message assigned for exceeding the maximum response time.

Note that automatic continuation will cause DirectRT to continue with the remainder of the trial if there is anything left to present. In a case where you would prefer that the remainder of the trial be skipped if the time is exceeded, then use !! rather than the single !

An alternative to using the ! symbol is to define -1 as a valid response code in the Time column cell of that trial. That way, only trials on which -1 is given as a valid response option will continue automatically after the maximum time has been reached. Like other rt related codes, if -1 is listed first, then it will be considered the correct response. This option can also be combined with the ! method if you want to define no response as correct but have automatic continuation regardless of the response. You can think of -1 as an actual "no response" button which is pressed at the maximum response time.

Fixed Response Window/Stimulus Duration with an RT

By default, DirectRT will continue to the next event when an valid keypress response occurs. You can optionally have DirectRT wait until a fixed amount of time has passed instead. Let's say you want to present a stimulus and define a keypress response, but you want that stimulus on screen for 2000ms—no matter how fast the response. To do this specify a max value of 2000ms in the MinMax field for the style code in the Styles file that matches the style code of the trial in the input file. Then, when you request the RT in the Time column cell for that trial your input file, simply add the keyword "full" at the end like this:

rt:53,44,full

This method can be combined with the automatic continuation method above. If you want a fixed response window but you want the stimulus to disappear after the response, then add the term "clear-1" as in the following:

rt:53,44,full,clear-1

This is a special case of a more general command used to clear a stimulus while waiting for an RT to occur. See Clear screen while waiting for an RT for more detail on this command.