Does level of processing affect the transition from unconscious to conscious perception?

Abstract Recently, Windey, Gevers, and Cleeremans (2013) proposed a level of processing (LoP) hypothesis claiming that the transition from unconscious to conscious perception is influenced by the level of processing imposed by task requirements. Here, we carried out two experiments to test the LoP hypothesis. In both, participants were asked to classify briefly presented pairs of letters as same or different, based either on the letters physical features (a low-level task), or on a semantic rule (a high-level task). Stimulus awareness was measured by means of the four-point Perceptual Awareness Scale (PAS). The results showed that low or moderate stimulus visibility was reported more frequently in the low-level task than in the high-level task, suggesting that the transition from unconscious to conscious perception is more gradual in the former than in the latter. Therefore, although alternative interpretations remain possible, the results of the present study fully support the LoP hypothesis

Is consciousness graded or dichotomous? a level of processing account

In this dissertation, we investigate whether consciousness is graded or dichotomous. Based on previous work and a level of processing framework, we hypothesize that consciousness in general, and visual experience specifically, can be conceived of as both graded and dichotomous. We present a series of experimental studies that provide support for this reasoning. We outline a set of future projects which can follow up on this research, and discuss the limitations of the current approach.Doctorat en Sciences Psychologiques et de l'éducationinfo:eu-repo/semantics/nonPublishe

Is consciousness graded or dichotomous?

This experiment aims to shed light on an ongoing controverse in the visual awareness literature. One aspect of the debate between the Global Workspace Theory and the Recurrent Processing Hypothesis is how the transition from unconscious processing to a conscious experience takes place. When postmasked stimuli are shown for parametrically varied durations, the former assumes an all-or-none transition (stimuli remain unconscious until the presentation duration is sufficient to generate a sudden clear experience), whereas the latter assumes a graded transition (the longer the presentation time, the gradually better the visibility). Here we intend to bring the two theories and their supporting evidence together, by taking the level of processing of stimuli into account. Participants performed a low-level (categorizing colored patches as red or blue) or a high-level task (categorizing numbers as smaller or larger than 5). Postmasked stimuli were presented for 10 ms up to 80 ms in steps of 10 ms. The psychophysical detection curve for the low-level task showed a graded pattern. The curve for the high-level task showed an all-or-none pattern. We hypothesize that high-level stimuli require access to a global workspace, whereas low-level stimuli can become conscious due to more posterior processing.info:eu-repo/semantics/nonPublishe

Perceptueel leren van taak-irrelevante subliminale stimuli

Taak-irrelevant perceptueel leren houdt in dat features van stimuli die niet geattendeerd worden toch geleerd kunnen worden. Dit uit zich door een verbeterde prestatie wanneer die specifieke features getest worden na training. Watanabe, Nañez en Sasaki (2001) en Seitz en Watanabe (2003) vonden dat ook subliminale features (i.e. oriëntatie van bewegende stimuli), die zelfs niet percipieerbaar waren wanneer ze geattendeerd werden, toch geleerd konden worden. Zij verklaarden dat dit leren gebeurde door de verspreiding van diffuse bekrachtigingssignalen, gemoduleerd door dopamine. Een biologisch meer plausibele mogelijkheid is echter dat het leren gebeurde door arousal, gemoduleerd door noradrenaline. In bovenstaande experimenten waren deze twee alternatieven niet te onderscheiden. Het doel van de huidige studie is dan ook de bekrachtigingsvisie te contrasteren met de arousalvisie. Hoewel de data een aantal beperkingen hebben, bleek de arousalvisie beter geschikt om de resultaten te verklaren. Vervolgens worden een aantal mogelijke neuronale mechanismen voorgesteld die dit leren concreet kunnen implementeren. Daarna wordt de rol van top-down aandachtsmechanismen besproken. De evidentie uit dit onderzoek en de bevindingen uit de literatuur leiden tot een denkkader dat een interactie tussen corticale top-down invloeden, sensorische informatie en subcorticale neuromodulatie veronderstelt. Hiermee wordt gepoogd visueel leren beter te begrijpen. Daarenboven worden mogelijke pistes voor verder onderzoek besproken.info:eu-repo/semantics/nonPublishe

Visual experience depends on level of processing.

The nature of our visual experience of the world has been examined thoroughly in both philosophy and cognitive psychology, but a number of issues remain the object of hot debates. One such pending issue is whether our visual experience is graded or dichotomous. Considerable evidence has been collected for both views. In a series of experiments, we tested whether the level of processing of the presented stimuli can account for seemingly contradictory results. Participants expressed either low-level judgments (color naming) or high-level judgments (number or word categorization) on the very same stimuli. We analysed both mean performance and mean subjective visibility ratings for stimulus durations ranging from 10 to 80 ms. Earlier work has shown that psychophysical curves exhibit a significantly more dichotomous transition in the high-level task than in the low-level task. The present research expands upon this work. Using different subjective measures, we examined whether participants use more intermediate scale points in the low-level condition than in the high-level condition, which would suggest a more graded perception for low-level stimuli and tasks. Results using confidence ratings were found to confirm this prediction. Altogether we propose that whether visual experience is graded or dichotomous depends on the level of processing of the stimuli during task execution. This has important implications for theories of consciousness that make claims about the graded vs. dichotomous nature of visual experience, such as global workspace theory.info:eu-repo/semantics/nonPublishe

Consciousness as a graded and an all-or-none phenomenon: A conceptual analysis

The issue whether consciousness is a graded or an all-or-none phenomenon has been and continues to be a debate. Both contradictory accounts are supported by solid evidence. Starting from a level of processing framework allowing for states of partial awareness, here we further elaborate our view that visual experience, as it is most often investigated in the literature, is both graded and all-or-none. Low-level visual experience is graded, whereas high-level visual experience is all-or-none. We then present a conceptual analysis starting from the notion that consciousness is a general concept. We specify a number of different subconcepts present in the literature on consciousness, and outline how each of them may be seen as either graded, all-or-none, or both. We argue that such specifications are necessary to lead to a detailed and integrated understanding of how consciousness should be conceived of as graded and all-or-none.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Is consciousness graded, dichotomous, or both?

This study aims to shed light on an ongoing debate in the visual awareness literature: is our conscious experience graded or binary? The Recurrent Processing Hypothesis assumes a graded transition (i.e. a linear relationship between stimulus duration and visibility). The Global Workspace Theory assumes an all-or-none transition (i.e. a non-linear enhancement of visibility once stimulus duration is sufficient). Here we intend to integrate the two theories and their supporting evidence, by controlling for the “level of processing” of the presented stimuli, a factor that was overlooked so far. To this end, we used a masked priming paradigm. Participants expressed either low-level judgements (color naming) or high-level judgements (number categorization) on the very same colored number stimuli. These were presented for 10 ms up to 80 ms. On every trial, participants were also asked to assess the subjective visibility of the stimulus in four steps, by means of the Perceptual Awareness Scale (ranging from “not seen” over “weak glimpse” and “almost clear image” to “clear image”). Non-linear models were fitted to the accuracy and the visibility data, respectively. We predicted and observed a graded access to consciousness in the low-level task, but a dichotomous access in the high-level task. This suggests that the Recurrent Processing Hypothesis and the Global Workspace Theory can be integrated if the level of processing is taken into account. We speculate that a more graded local workspace is sufficient for conscious access in low-level tasks, whereas in high-level tasks this requires an all-or-none global workspace.info:eu-repo/semantics/publishe

Subjective visibility depends on level of processing

Is visual awareness graded or binary? Experimental work has provided support for both possibilities, leading to two coexisting but contradictory theoretical accounts. Here we pro- pose a promising candidate factor through which to integrate both accounts: the depth of stimulus processing required by the task. We compared color identification (a low-level task) with numerical judgements (a high-level task) performed on the very same colored number stimuli. Psychophysical curves were analyzed for both objective discrimination performance and subjective visibility ratings on a trial-by trial basis. We observed a graded relationship between stimulus duration and visibility in the low-level task, but a more non-linear relationship in the high-level task. Both patterns of results have previously been consistently associated with the graded and the dichotomous account, respectively. Follow-up experiments that manipulate the level of processing can further unify previously inconsistent results, thus integrating two major theories of visual awareness.info:eu-repo/semantics/publishe

Experiencing more complexity than we can tell

The notion of unreportable conscious contents is misguidedly premised on the idea that access necessarily follows phenomenal representation. We suggest instead that conscious experience should be viewed as a constructive, dynamical process that involves representational redescription: The brain continuously and unconsciously performs signal detection on its own representations, so developing an understanding of itself that subtends conscious experience. Cases where phenomenality seems to overflow access are thus illusory and depend on interactions between task instructions and stimulus complexity. We support this perspective through recent evidence suggesting that properly graded, qualitative subjective reports appear to be exhaustive in revealing conscious knowledge.SCOPUS: no.jinfo:eu-repo/semantics/publishe