By nicky6056 - 9/28/2015
Hi, I'm trying to program an experiment similar to the 'staircase method' experiment in the inquisit task library, except rather than using shades of colour, using electric shock stimuli to determine someone's pain threshold. This will involve sending through an electric shock, asking the participant whether it is painful, and if they say 'no' increasing the shock level until the first 'yes' (called a reversal), and then having six reversals before determining the threshold. I have used inquisit with the parallel ports to send shock stimuli in the past, but inquisit sees these as individual stimuli, rather than as having an inherent order like say the colour numbering (where 0 = none of the colour, 255 = maximum amount of that colour), so I'm not sure if it will be possible to do the conditional branching in a method similar to the 'staircase method' experiment, or whether it is possible at all in inquisit. Has anyone had any experience with numbering ported stimuli, and have an idea of whether it will be possible for inquisit to work out what an increase or decrease along this order would be? Thank you very much in advance!
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By Dave - 9/28/2015
Your shock generator is responsible for administering the desired intensity of the electrical shock. You need to set up your generator to deliver different intensities based on the signal that it receives from Inquisit. A <port> element, just like any other stimulus element, can of course have multiple items, i.e., it can send a different signal to your generator based e.g. on participants' (prior) responses. I don't quite understand your point about "inherent order". <port> elements can send 8-bit TTL signals -- expressed in decimal integers, those values range from 0 to 255 and thus there is inherent order. You can set up your shock generator to deliver the lowest intensity when it receives the signal 1 from the port and increase intensity as the value of the signal increases.
Hope this helps.
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