Operant conditioning and discrimination of alpha: Some methodological limitations inherent in response-discrimination experiments.

Abstract

Studies on the operant conditioning of central nervous system activity have produced results interpreted as demonstrating that responses, certain properties of responses, or response-produced stimuli can function as discriminative stimuli. It is assumed that the feedback stimulus in biofeedback makes the subject aware of the internal response and that by becoming aware of the response, the subject can acquire voluntary control over it. In this context, awareness is operationally defined as the ability to use the response as a discriminative stimulus. Since direct evidence for the assumed relationship between control and discrimination is lacking, an attempt was made to test the hypothesis that discrimination of a response automatically leads to control over that response. The discriminative stimuli were the presence and absence of occipital alpha electroencephalograph (EEG) activity. Data from two experiments are reported. The first study, employing naive subjects, was designed to answer the following questions: (a) Since pilot data indicated that subjects seemed to match their responses to the more probable type of trial, would increases in the probability of a correct response result when the probabilities of alpha and nonalpha trials were held near .50? (b) If correct responding does increase, would performance of these subjects in an alpha feedback task be enhanced relative to that of subjects not previously given discrimination training? and (c) If subjects could not learn the discrimination task, would feedback training enhance their performance in a subsequent discrimination task? Results from this study indicate that holding the probabilities of alpha and nonalpha discrimination trials near .50 results in an absence of learning curves, but leaves open the possibility that sophisticated subjects are capable of discriminating alpha and nonalpha activity. The second study deals with two questions: (a) Can sophisticated subjects learn to discriminate occipital alpha activity from nonalpha activity? and (b) Does the procedure of providing subjects with salient stimuli, contingent on the presence and absence of alpha activity, establish stimulus control of the presence and absence of alpha activity? Results indicate that it is not possible to conclude that subjects can learn to discriminate alpha and nonalpha activity. However, learning to increase percent-time nonalpha or decrease percent-time alpha with respect to baseline levels by means of EEG-contingent stimulation provides subjects with the ability to suppress percent-time alpha in the absence of feedback. Information gained in both studies through subject interviews indicates that subjects most often acquired their control of alpha activity during feedback by a specific strategy and then used the strategy during the stimulus-control tests.

Psychophysics of EEG alpha state discrimination

“…The present study is the first to demonstrate that human subjects can learn to discriminate alpha activity since Kamiya (1962; 1968; 1969; 2011), despite at least three failed attempts at replicating the phenomenon (Legewie, 1975; 1977; Orne & Wilson, 1978; Cott et al, 1981). The likelihood that true learning of an EEG state discrimination skill is taking place is supported by the significant ratio of criterion to non-criterion sets and sessions, the lack of effect of muscle artifact, and the significant learning curve effect (figure 1).…”

“…Another study (Cott, Pavloski, & Black, 1981) failed to demonstrate discriminative learning of the alpha rhythm, but differed substantially from Kamiya’s original study in defining an alpha state as one-half second of high absolute alpha power. Kamiya (personal communication, 2006) argued that one-half second is barely at the threshold of a subject’s ability to discriminate a state.…”

“…In addition to Cott et al (1981), two additional failed replication efforts were published, although with very limited methodological detail (Legewie, 1975; 1977; Orne, Evans, Wilson, & Paskewitz, 1975, cited in Orne & Wilson, 1978). However, Orne & Wilson (1978) mentioned that one complicating factor was that the amount of alpha in most subjects increased over several sessions, to the point where it was difficult to find periods of non-alpha lasting even 1–3 seconds by the third session.…”

Identifying Indices of Learning for Alpha Neurofeedback Training

“…A review of the literature reveals that the three most common measures used to identify changes in alpha activity are percent time (e.g., Angelakis et al 2007;Cott et al 1981aCott et al , 1981bYamaguchi 1980) amplitude (e.g., Cho et al 2008;Putnam 2000) and integrated alpha (e.g., Knox 1982;Plotkin and Rice 1981;Tyson 1987). Percent time refers to the percentage of time participants spend above or below the target threshold when attempting to enhance and/or inhibit their alpha.…”

Interactions Between Discrimination and Control of EEG Alpha

“…The advantage (% Adv) of using this information was significantly different from zero for ITIs of 8. (Cott, Pavloski, & Black, 1981;Orne & Wilson, 1978). Since it was unclear where the boundary between short and long was between these extremes, it was reasoned that an effective p = .10 alpha-level was justified if a one-tailed test was not, because type II error for these comparisons Vol.…”