I'm doing a lexical decision task using e-prime on a laptop. Following the steps given by Wittenbrink, Judd and Park (1997). The prime appears 15 ms on the screen.
I am not sure that I understand your question. If by "recognize" you mean "become aware of," then it is not subliminal. If you give information about it, it might defeat the purpose of your research. Could you give more details?
Thanks for your answer Gonzalo Munevar. When i said "recognize it" i mean participants can actually read the prime, but i don't know if they are aware that the prime interferes with the task that we are asking them and if they do the association that we want to test.
Hi Rita,
It is of crucial importance that the task your subjects are faced with makes sense to them. I guess what you are really asking is something along these lines "Since the subjects are able to read the prime, should I mention in the instructions I give them the fact that a prime is presented before the target?" rather than "Since the the subjects are able to read the prime, are they aware it interacts with the task?". In my opinion, the answer to the former is yes, while the answer to the latter is not necessarily yes (though I would guess it is for most of the subjects).
Anyway, as Gonzalo Munevar puts it, if the subjects are able to read the prime, you can definitely NOT speak of subliminal priming.
Now, if the presentation time was actually of 15 ms it would be surprising that the subjects are able to read the prime. However, I contend that the presentation times you ACTUALLY have are most likely in the range of 27 to 40 ms (in the most optimistic case, and even as high as 33-67ms in the most realistic case). This is because on a laptop the screen refresh rate is at best of 75Hz (and most likely 60Hz).
If you want to ensure subliminal primes are presented I suggest the following:
1° use an external, CRT screen with a (decently) high refresh rate (e.g., at least 133 Hz, some models go up to 200Hz)
2° turn on the Time Audit logging in E-Prime to be able to assess the actual presentation time of your primes (asking E-Prime to present a prime for 15 ms does not suffice to ensure it will be presented for 15 ms ; for instance, with a refresh rate of 75Hz, the display times are multiples of 13.33 ms, so your stimulus will be presented in the best case scenario for 27 ms (and sometimes for 40 ms)
Once you are happy with the presentation times you do actually get (explore the Time Audit logs), go to 3°
3° run a control experiment first where you present only the prime (no target) and ask participants to report the prime; if they are able to report the prime, then you won't be able to speak of subliminal priming in your priming (i.e., other) experiment (if they all fail to report the prime even when given high incentives, then the display duration of your prime is low enough to ensure you will deal with subliminal priming in your main experiment). Reading Jacoby & Whitehouse, 1989 (Jacoby , L.L., &Whitehouse, K. (1989). An illusion of memory: False recognition influenced by unconscious perception. Journal of Experimental Psychology: General, 118, 126-135) may be of help here.
HTH.
Cheers,
Serban
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