Conscious and nonconscious processes: An ERP index of an anticipatory response in a conditioning paradigm using visually masked stimuli

Abstract

This study investigates the nonconscious elicitation of a previously conditioned response by using a differential conditioning paradigm with visually masked affectively valent facial schematics. Electrodermal (skin conductance response [SCR] and brain (event-related potential [ERP]) activity were main dependent measures. Following a preconditioning phase in which subjects viewed energy masked pleasant and unpleasant facial schematics, conditioning with an aversive shock was established to unmasked presentations of an unpleasant face in a partial factorial design. A postconditioning phase of masked presentations, when compared with the preconditioning phase, revealed how the conditional effect within awareness might affect the same stimuli when presented outside awareness. An adaptive staircase technique was used to establish individual threshold levels, which represented a methodological advance over procedures typically used in visual masking research. The results revealed that responses to the CS+ (unpleasant face) changed significantly in predicted directions from preconditioning to postconditioning phase when compared with responses to the CS- (pleasant face). The SCR results systematically replicated recent Ohman, Dimberg, and Esteves (1988) findings, with the pattern of responses resembling a resistance to extinction effect. A new finding emerged for the brain responses. For the CS+, distinct slow wave activity occurred just before the point at which the shock had been delivered in the conditioning phase; no such activity was found for the CS-. This slow wave activity is similar to what has been described by others as an expectancy wave. The results indicate that an anticipatory process, as indexed by different physiological systems, can be elicited entirely outside awareness. Implications are discussed in regard to the nature of conscious and nonconscious processes.

I Like It, but I'm Not Sure Why: Can Evaluative Conditioning Occur without Conscious Awareness?

“…When this method is used there is evidence that a CR can be evoked by a CS presented out of awareness if the CS-UCS association was formed in awareness (Öhman, Dimberg, & Esteves, 1988). Wong, Shevrin & Williams (1994) replicated this finding and discovered brain responses to subthreshold presentations of the CS. Esteves, Dimberg and Öhman (1994a) found that CRs to angry face CS+s survived backward masking but CRs to happy face CS+s did not (see also Esteves, Parra, Dimberg & Öhman, 1994b).…”

The scientific legacy of Sigmund Freud: Toward a psychodynamically informed psychological science.

“…Thus, a conditioned stimulus can elicit affect, as assessed electrophysiologically, even when presented outside of awareness. Numerous other studies have produced similar results (see J. Weinberger, in press ;Wong, Shevrin, & Williams, 1994 ) with dependent variables ranging from skin conductance to facial electromyography (EMG, which measures facial muscle indicators of emotion) to evoked-related brain potentials (ERPs). Other studies show that classically conditioned emotional responses can be not only elicited but acquired without consciousness (e.g., Bunce, Bernat, Wong, & Shevrin, 1995 ;Esteves, Dimberg, & Ohman, 1994 ).…”

Strength of visual percept generated by famous faces perceived without awareness: Effects of affective valence, response latency, and visual field

“…There is much evidence that facial expressions can be detected pre-consciously and can influence psychophysiological and behavioural responses without awareness of the particular expression (e.g., Dimberg & Ohman, 1996;Dimberg, Thunberg, & Elmehed, 2000;Johnsen & Hugdahl, 1991Mogg & Bradley, 1999;Murphy & Zajonc, 1993;Niedenthal, 1990;Ohman, Esteves, & Soares, 1995;Robinson, 1998;Saban & Hugdahl, 1999;Whalen et al, 1998;Wong, Shevrin, & Williams, 1994). All of these studies presented masked faces for very brief exposure duration (target-to-mask stimulus onset asynchrony [SOA] of less than 35 ms).…”