Discussion post I submitted for my Atlantic University TP6100 Course – February 4, 2020.
Why do forced-choice experiments provide better/clearer statistical evidence than free-response tasks?
Before getting into the gist of the question, it’s important to distinguish “forced choice” and “free response” experiments as it relates to parapsychology. The online Psychology Dictionary defines ESP Forced Choice tests as “Parapsychology experiments where a participant calls are restricted to predetermined targets” (https://psychologydictionary.org/esp-forced-choice-test/).
Forced choice parapsychology ESP experiments were revolutionized when Karl Zener of Duke University settled on 5 different card design choices of “elementary geometrical symbols” as a replacement for traditional playing cards as noted by Irwin & Watts (2007, p. 51-52). Subjects would attempt to guess “the identity of each card in a shuffled deck,” which consisted of a total of 25 cards, 5 of each of the designs (2007, p. 52).
With the advent of the computer era came Random Number Generators (RNG). According to Broughton, in the late 1960s, a rudimentary electronic “shoe-box-sized aluminum device” with “four colored lights in a row and four largish buttons, one below each light,” was used for precognitive research (1991, p. 123). Now, instead of shuffling card decks, a computer-generated testing device could be used that took a number of potential human variables out of the equation for psi research. The test was simple. The subject would try to guess which light would blink next by pushing the button prior to it flashing. Broughton noted, “This modest experiment, which he undertook without much fanfare [in 1969]…marked the beginning of a second revolution in ESP research and the beginning of the contemporary period for forced-choice guessing” (1992, p. 124).
Irwin & Watts define free-response experiments as those controlled “tests in which the range of extrasensory targets is unknown (and hence conceptually unlimited) to the subject” (2007, p. 48). While free-response experiments revolutionized the early days of psi research, they fell out of vogue a bit with the advent of the forced-choice experiments mentioned above. According to the authors, free-response experiments had a renaissance of sorts, however, with the introduction of technology and the development of the Ganzfeld technique. “The popularity of free-response techniques…has revived in the last few decades, particularly in the context of research on extrasensory experiences during carious altered states of consciousness” (2007, p. 54).
Forced-choice experiments provide clearer statistical results primarily because of significantly fewer variables involved in an experiment and the amount of control they bring in contrast to free-response tasks. Force-choice studies can be considered “quantitative” research, in that their primary aim is to generate as much data as possible in order to crunch the numbers and produce statistical results of psi experiments.
In the ESP Cards or the RNG box discussed above, for example, because of the ease of which the experiments can be conducted, the number of trials is significantly large. For example, in the RNG “box” mentioned above, Broughton relays a story where over the course of several months, 3 volunteers completed 63,066 trials (1991, p. 124). And Irwin & Watt discuss an experiment using the Zener ESP Card with a trial size of 17,250 (2007, p. 54).
If forced-choice experiments correlate to quantitative studies, free-response tasks are similar to qualitative research. Free-response studies tend to be more complex and can be much more subjective. Instead of choosing between 5 card designs or 4 lamps, in a free-response task, a subject or “receiver” is asked to describe what they visualized, for example, during a period of time when a “sender” in another room sent them telepathically images from a randomonly-generated photograph or drawing. The receiver is then shown 4 images, one of which is what the sender relayed, and they are asked to rank the images in the order from most likely to less likely of what they “saw.” An independent judge or panel of judges then determine how close their verbatim response of the receiver is to the image they selected. If they believe it to be correct, they mark it as a “hit.”
There are a lot of moving parts and subjective pieces with a free-response experiment Throw in such elements as a Ganzfeld effect, and you’ve got a much more costly experiment than forced-choice, and, as such, they clearly aren’t able to conduct anywhere near their trial sizes. Nor can they produce similar statistical results as the forced-choice experiments. Free-response experiments are a much longer and subjective process than simply recording whether or not the subject selected the right ESP card or guessed correctly the next flashing light.
ReferencesBroughton, R. (1991). Parapsychology: the controversial science. New York, NY: Ballantine Books.
Irwin H. & Watt, C. (2007). An introduction to parapsychology. Jefferson, NC: McFarland & Company, Inc.
Psychology Dictionary (n.d.). “ESP force-choice Test.” Retrieved February 4, 2020 from https://psychologydictionary.org/esp-forced-choice-test/