If you do have two blocks that contain very different stimuli the approach to take is to control the number of times each block repeats using an outer-loop. The outer “blocks” loop then takes a (meta) “conditions” file that specifies which of the conditions files will be loaded in each block. Then you can set the conditions files in your blocks loop to control the block-level changes. Instead of a Routine for each block, create a Routine for all your trials and make it behave differently across the blocks: in a Numerical Stroop task where both valid/congruent and incongruent trials contain two numbers and a keyboard response), this is not the most efficient approach. However, if both blocks contain the same stimuli/elements (e.g. When people have several “blocks” the natural move is to add separate routines for those blocks: Note: these are all cases where the components would be identical between blocks. e.g.Ī block of faces to recognize or a block of housesĪ block of Stroop task in English and a block in FrenchĪ block of valid trials versus a block of invalid trials ¶ Block designs and counterbalancing ¶ Randomized block designs ¶Ī block design is where we have sets of similar trials organized into blocks rather than having trials interleaved. The data tab of the keyboard component, to store the correct answer click “store correct” if the correct answer changes trial by trial use a variable that is set from the spreadsheet. In our keyboard component, we can then select “Store correct” and use the variable $corrAns in the field. The corrAns column tells us which key is the correct answer. In this example, the numerically larger number is the correct answer. So, we add a column to our spreadsheet to indicate what the correct answer is. In our experiment, the participant can press either the left or right arrow key. It is very easy to store accuracy from a keyboard in PsychoPy. When you are finished, come back to the main session and collect one run of your task so that we can talk through the data file. Make the size (letter height) of the numbers change trial.Īdd a column to the conditions spreadsheet to note if this trial is congruent (numerically larger number is also physically larger) or incongruent (numerically larger number is physically smaller).Īdd an instructions routine and a thanks routine to the experiment. By default “participant” and “session” are gathered - and these are used to set the filename of that participant. age) ¶Įvery experiment starts with a dialog box to gather some info about the participant/experiment. Let’s start by presenting a different pair of numbers on each trial and allowing the participant to press the left and right arrow keys to indicate a number. Then make sure to use that variable to set the parameter of a component on every repeat of your loop. Once we have inserted a loop we can add a spreadsheet of trials to the “conditions” field. Each header is a variable, each row corresponds to the value of that variable on each trial. If something changes trial-by-trial, we make a spreadsheet (this can be made in Excel). To present several trials, add a loop around the routine to repeat. Changing things trial-by-trial (the “conditions” file) ¶ an Inter-Trial-Interval presenting a fixation cross). Creating a routine ¶Ī Routine is the basic building block of PsychoPy experiments. To start making an experiment we add routines to our flow and add components to our routines. What makes a PsychoPy experiment? ¶Ī builder experiment has three main sections. In this demo we will work through making a Numerical Stroop task in PsychoPy. Building better experiments ¶ Using Builder ¶Īll the base knowledge we assume at the start of this workshop can be learned from this 15 minute video
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