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Ganzfeld studies of Extra-Sensory Perception (ESP). Third methodological issue. Test for ESP
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Ganzfeld studies of Extra-Sensory Perception (ESP) Third methodological issue
Test for ESP • Based on the assumption that if ESP exists its signal is probably quite weak and usually drowned out by background stimuli. If we reduce this stimuli and create an environment of sensory deprivation ESP signals may come through.
P’s relax alone on a comfortable chair in an isolated room • Halved ping-pong balls are placed over their eyes and red light shone into their face • P wears headphone playing white noise to experience mild sensory deprivation • Sender and receiver • Zener cards
Controversies surrounding Ganzfeld There are 4 main controversies surrounding Ganzfeld research: 1. Replication 2. Experimental design 3. Experimenter bias 4. Factors (e.g. prior lab experience feeling/perception personality bias) Blue = AO2/3
Controversy 1 – Replication • In early trials by Rhine ESP was as high as 40% (chance being 20%). • Many claim that due to tighter controls these findings could not be found now. • However - a review by Parker& Brusewitz (2003) quote 6 more case studies of high ESP.
Controversy 2 – Experimental design • Most Ganzfeld studies use a forced- choice (Zener cards) • There is an argument that the forced- choice design will produce more correct responses as the targets are known. (Honorton and Ferrari - MA) • However Milton (1997) looked at free-response designs and found similar levels of ESP.
Controversy 3 – Experimenter bias • Rosenthal & Harris (1988) believed that the expectations and attitudes of experimenters might influence the results. • However Parker & Brusewitz (2003) claim that experimenter effects cannot explain psi effects if controls are in place for that study.
Controversy 4 – Can factors bring about positive results without being a case for ESP? Dalton (1997) looked at several factors that lead to success in Ganzfeld studies: • Prior experience • Practice of a mental discipline (e.g. meditation) • Prior lab experience • Feeling/perception preferences