![]() ![]() So, how to switch between these files? That’s the trick and that’s what the other file is used for. In a real experiment you’d probably also have response keys andsuchlike as well. In this example we can just use a variable stimFile with values like stims/face01.jpg and stims/face02.jpg while the housesBlock file has stims/house01.jpg and stims/house02.jpg. The facesBlock, and housesBlock, files look more like your usual conditions files. So, how do you get the block to change from one set of images to another? To do this create three spreadsheets, one for each block, determining the filenames within that block, and then another to control which block is being used: You can also have additional Routines like something to inform participants that the next block is about to start. randomly selecting a number of images) but then you will have a second loop around this to define how the blocks change. You can add a loop around your trials, as normal, to control the trials within a block (e.g. This example is included in the Builder demos, as of PsychoPy ® 1.85, as “images_blocks”. It would be tempting to create a Routine called presentFace and another called presentHouse but you actually want just one called presentStim (or just trial) and then set that to differ as needed across different stimuli. For instance, let’s imagine you’re trying to create an experiment that presents a block of pictures of houses or a block of faces. Try to define your trials with a single Routine. ![]() The key thing to understand is that you should not create different Routines for different trials in your blocks (if at all possible). This isn’t all that hard, although it does require a bit of thinking! Blocking similar conditions ¶ Many people ask how to create blocks of trials, how to randomise them, and how to counterbalance their order.
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