Dear Cedrus Support People,
Hope you all had a nice Christmas/ festive break.
I am writing in the hope that you might be able to help me with an experiment I am trying to design:
Purpose: Undergraduate Final Year Dissertation project
Participants: Children with and without Autism Spectrum Disorder
Operating System: PC – Windows XP
SuperLab Version: 4.0.7b
Level of Expertise: Novice – this is the first experiment I have tried to create using SuperLab
Type of Experiment: Change Blindness Task – Flicker Paradigm
Stimuli: Bitmap Images
Response Mode: Just keys on Keyboard (no external devices)
Details (what I want experiment to do):
- A black fixation cross will appear in the center of the display – the participant will press the ‘1’ key when ready to proceed.
- A photographic scene (version A) will then be presented for 400 ms
- Followed by a grey masking screen for 100 ms.
- The alternate version of the scene (version B) will then be displayed for 400 ms,
- followed again by a grey masking screen for 100 ms
- This “flicker” sequence will be repeated until the participant detects the ‘change’ between these 2 scenes. (e.g. object in scene appearing/ disappearing)
- Participants will press the space bar when they spot the ‘change’ (the reaction time of interest is the time between initial onset of the first photo and the point in time in which the spacebar is pressed)
- They will then be presented with a static version of the photo (Version A) and asked to report the location of the change by pointing at the screen.
- A timeout error will be recorded if the participant does not spot the change in 30 seconds.
- This process will be repeated for ~ 24 trials.
I attach the experiment I have created thus far (as a single .SL4 file and as an experiment package). It contains only 2 trials at this stage. I have managed to create the ‘flicker’ effect by using the feedback commands to instruct the events to repeat themselves . . . . but have been unsuccessful in the following:
A. RESPONSE RECORDING – I need to record the time taken between the onset of the very first stimulus photo and when the participant presses the spacebar. The response times recorded do not look right. They seem too short. Is the timer able to record this response time across multiple cycles of the same trial? (Detail # 7)
B. TIMEOUT – I cannot seem to program each trial to end after 30 seconds if participant has not responded (Detail # 9)
I am also unsure whether I have created the experiment correctly thus far – it has crashed a few times and I am not sure if that is due to a mistake on my part or not.
I am currently based in Dubai and I am not sure whether there is any local support I can tap into ‘on the ground’. Unfortunately my tutor at my university has not been able to help me. I feel that I am feeling my way in the dark a little bit.
Any advice would be greatly appreciated,
Thanks in advance