Subjective and objective learning effects dissociate in space and in time

Abstract

Perceptual learning not only improves sensitivity, but it also changes our subjective experience. However, the question of how these two learning effects relate is largely unexplored. Here we investigate how subjects learn to see initially indiscriminable metacontrast-masked shapes. We find that sensitivity and subjective awareness increase with training. However, sensitivity and subjective awareness dissociate in space: Learning effects on performance are lost when the task is performed at an untrained location in another quadrant, whereas learning effects on subjective awareness are maintained. This finding indicates that improvements in shape sensitivity involve visual areas up to V4, whereas changes in subjective awareness involve other brain regions. Furthermore, subjective awareness dissociates from sensitivity in time: In an early phase of perceptual learning, subjects perform above chance on trials that they rate as subjectively invisible. Later, this phenomenon disappears. Subjective awareness is thus neither necessary nor sufficient for achieving above-chance objective performance.consciousness | psychophysics | Signal Detection Theory O ur perceptual apparatus is constantly shaped by experience. This fact has been shown, for example, in experiments investigating perceptual learning, where practice on a sensory task leads to increases in perceptual sensitivity (1). Although perceptual learning is a well-studied phenomenon, the question of how it changes subjective awareness has rarely been addressed. Do we actually "see more" after training? Apart from anecdotal reports pointing in this direction, a quantitative analysis of the effects of learning on subjective awareness is largely missing (2) because studies in perceptual learning have almost exclusively focused on objective task performance [i.e., sensitivity in terms of signal detection theory (3)]. However, studies from a different line of research, namely those investigating conscious perception, have found that objective performance in a task and awareness of the stimuli on which the task is performed can dissociate. Such is the case in blindsight (4) but also is found in normal observers (refs. 5-7 but see ref. 8). These data demonstrate that these two aspects of perception cannot be treated as being equivalent. We have recently shown that subjects can be trained to perform on and to see stimuli that are initially invisible to them (9). We thus hypothesize that awareness is trainable, a conclusion that is in accordance with recent findings in blindsight patients (10). However, the time course of those learning effects has not been explored, i.e., whether the improvements in sensitivity and subjective awareness depend on each other. In particular, changes in sensitivity could be a prerequisite for changes in subjective awareness. Alternatively, it could be necessary to subjectively see a stimulus in order for changes in sensitivity to occur. Last but not least, training could affect sensitivity and subjective awareness in parallel without any mut...

Differential BOLD Activity Associated with Subjective and Objective Reports during “Blindsight” in Normal Observers

“…Blindsight patients deny any subjective visual experience while successfully performing objective visual tasks (Sahraie et al, 1997;Stoerig and Cowey, 1997;De Gelder et al, 2008). Similar, blindsight-like dissociations (also termed implicit perception) have been documented in healthy individuals (Meeres and Graves, 1990;Kolb and Braun, 1995;Lau and Passingham, 2006;Schwiedrzik et al, 2011). Methodologically, such dissociations impose serious difficulties on the search for the neuronal correlates of subjective visual experience.…”

Sensory noise increases metacognitive efficiency

“…Rather, perceptual learning was used as a tool that allowed us to decrease sensory noise in our model. Several previous studies have combined confidence ratings and perceptual learning (Guggenmos, Wilbertz, Hebart, & Sterzer, 2016;Schwiedrzik, Singer, & Melloni, 2011;Solovey et al, 2016;Zizlsperger, Kümmel, & Haarmeier, 2016) but while they found important effects of learning on the overall confidence level, none investigated how training affects metacognitive efficiency.…”

“…However, our results demonstrate that while metacognitive judgments may indeed be related to consciousness, they cannot generally be used as a direct measure of consciousness (Jachs, Blanco, Grantham---Hill, & Soto, 2015). Indeed, perceptual learning has been argued to increase consciousness (Schwiedrzik et al, 2011) but, as seen here, decreases metacognitive efficiency. We see metacognitive scores as invaluable in constructing and testing models of decision making but remain agnostic about their relationship to constructs such as consciousness and working memory.…”

Learning improves conscious access at the bottom, but not the top: Reverse hierarchical effects in perceptual learning and metacognition

“…Consistent with the latter prediction, studies investigating the VPL of simple object properties (e.g., shape) have reported accompanying improvements in measures of metacognition (Bertels, Franco, & Destrebecqz, 2012;Schlagbauer, Muller, Zehetleitner, & Geyer, 2012;Schwiedrzik et al, 2011). However, does the VPL of high-level stimulus properties fail to improve accompanying metacognition?…”

“…Investigating this issue, two parallel bodies of research have recently emerged. One investigates whether conscious stimulus awareness is necessary for VPL (e.g., Seitz et al, 2009;Watanabe et al, 2001), while the other investigates whether conscious stimulus accessibility can be improved by VPL (e.g., Schwiedrzik, Singer, & Melloni, 2011).…”