The notion that psi may be able to function without conscious intent to mediate adaptive outcomes is a predominant feature of several theories of psi. In particular, Stanford’s ‘Psi-mediated Instrumental Response’ (PMIR) model predicts that psi can operate in the absence of conscious awareness, facilitating advantageous outcomes for the organism by triggering pre-existing behaviours in response to opportunities or threats in the environment. To test some assumptions of this model, Luke and colleagues carried out 4 studies involving a 10-trial computer based protocol in which participants were asked to indicate their preferred images from sets of four geometric patterns. Unbeknown to the participants, this constituted an implicit, forced-choice precognition task as after they had made each preferential choices, the computer randomly selected one of the four images as a target. In contingent conditions, participants whose hit rate at the end of the 10 trials exceeded the mean chance expectation were directed towards a positive outcome task of rating erotic or cartoon images, whereas those who scored below the MCE took part in a negative outcome task consisting of a boring number vigilance activity. Taken together, the four studies yielded highly significant evidence of an implicit precognition effect. However, participants in non-contingent conditions, who were allowed to leave the experiment early rather than take part in a contingent outcome task, performed marginally better than those in contingent conditions. This raised questions over the assumptions of the PMIR model and called for further testing.
The present study therefore attempted to clarify this issue by refining the experimental design and using a more carefully composed contingent reward task structure using images from the International Affective Picture System. The number of trials per participant was increased from 10 to 15 to increase statistical power, whereas all other design elements remained consistent with the original studies. Fifty participants completed a battery of questionnaires and a 15-trial computer-based implicit psi task with a graded positive or negative contingent reward outcome task. The results showed that participants scored more hits on the tacit precognition task than would be expected by chance but the extent of the outperformance was not statistically significant (mean hit rate = 4.02, MCE = 3.75, t[49] = 1.14, p = 0.13, one tailed). Interestingly, participants were shown to perform almost exactly at chance levels over the final 5 trials which had been added for the present study. With regards to individual difference correlates of psi task performance, a significant positive correlation was found between participants’ hits on the implicit precognition task and their scores on Goldberg’s measure of openness to experience (r = .29, p = .02), used here as an experimental proxy for latent inhibition, a factor hypothesised to diminish an organism’s receptivity to psi stimuli. However, correlations between psi score and beliefs about luck, psi, paranormal phenomena and creativity were all found to be non-significant. These findings are interpreted in terms of their support for Stanford’s PMIR model.