Nora Koster; Uwe Mattler; Thorsten Albrecht

Visual experience forms a multidimensional pattern that is not reducible to a single measure: Evidence from metacontrast masking

publication date
March 2020
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A metacontrast masking paradigm was employed to provide evidence for the richness and diversity of our visual experience. Square- and diamond-shaped targets were followed by square- and diamond-shaped masks at varying stimulus onset asynchronies (SOAs), resulting in shape-congruent and shape-incongruent trials. In Experiment 1, participants reported in each trial how they perceived target and mask. After extended training, seven different aspects of the target could be distinguished as specific percepts in this metacontrast masking paradigm. These percepts encompass aspects including the temporal distance between both stimuli, the perceived contrast of the target, and motion percepts resulting from the interplay between the target and mask. Participants spontaneously reported each of these percepts, and the frequency of reports varied systematically with SOA and the congruency between target and mask. In Experiment 2, we trained a new group of participants to distinguish each of these target percepts. Again, the frequency of reports of the specific percepts varied with SOA and congruency, just as in Experiment 1. In a last session, we measured objective discrimination performance yielding the typical individually different masking functions across SOAs. An examination of the relation between the frequencies of reports of subjective percepts and objective discrimination performance revealed multiple dissociations between these measures. Results suggest a multidimensional pattern of subjective experiences under metacontrast, which is reflected in dissociated subjective and objective measures of visual awareness. As a consequence, awareness cannot be assessed exhaustively by a single measure, thus challenging the use of simple one-dimensional subjective or objective measures in visual masking.


We developed a new approach to examine the phenomenological experience of simple visual stimuli that takes into account requirements of naturalized phenomenology to overcome the limitations of previous phenomenological approaches. We applied this approach to investigate the richness of phenomenological experience in a metacontrast masking paradigm with simple stimuli. First, we collected spontaneous reports of percepts of naïve observers who were only trained to focus on the target stimulus in the metacontrast sequence. The frequency of reports of individual percepts was systematically modulated by the experimental variables SOA and congruency. Second, we had naïve raters classify the individual descriptions of the percepts into seven percept categories that we found in a scattered literature on metacontrast. Third, we trained a new sample of participants to report the appearance of each of the seven percepts and observed how the frequency of reports of each percept varied with SOA and congruency. The correspondence between the characteristics of the spontaneous and the instructed reports indicates that we are reliably measuring specific stable entities and thus validates our approach, although these entities are subjective experiences that vary considerably among participants. The comparison of the characteristics of the percepts with the characteristics of similar reports in the literature revealed that our approach produces meaningful results. Findings provide evidence for the view that phenomenal consciousness forms a multidimensional pattern that is not reducible to a single measure. This multidimensionality has far-reaching implications: First, any measure of consciousness that claims to be exhaustive has to capture a multivariate pattern of visual experiences, which cannot be done by single one-dimensional subjective or objective scales. Second, any approach to demonstrate a dissociation between indirect and direct effects of masked primes has to consider carefully, which dimension of the multivariate pattern is the most relevant. Third, multidimensionality provides new boundary conditions for theory building. A comprehensive model of masking must allow for multiple visual experiences and must be able to explain different masking time courses for multiple stimulus dimensions.


Vision therapy is well worth the response, time and effort. Our Son had a hard time focusing and writing neatly. After vision therapy Seth could complete a task in half the time if previously took. His abilities to focus improved greatly and so did his handwriting.

Also, he was better at listening. As a parent, we wanted learning to be fun for our Son, and vision therapy made this possible.

Amanda T.

Vision Therapy is well worth the expense, time and effort. Our son had a hard time focusing handwriting neatly. After vision therapy Seth could complete a task in half the time it previously took his abilities to focus and improved greatly and so did his handwriting.

Also, he was better at listening. As a parent you wanted learning to be fun for our son and vision therapy made this possible.

Alexa H.

Vision Therapy has given or son the tools he needs to be able to scan and read the written word more effectively and efficiently.

He love working with John and these working sessions give him the motivation to gladly work on his homework assignments.

It amazed us to see the difference in the tracking of his eyes and along a line of it's from the beginning to the end of the treatment.

Dr. McBryar , Kristen and John  are all marvelous and we would recommend them to anyone I only wish that we would have found them sooner!

Charlotte M.

Prior to coming to the institute for vision development my son complained of daily headaches. Therapy has eliminated his headaches completely. I love knowing my son is able to learn pain-free for the rest of his life because of the work that has been done over just a few weeks in this office. He he absolutely loved coming that didn't even feel like going to a doctor or therapy. We are grateful for the relief he was able to find by coming here.

Thank you!

Olivia C.

Seems much less frustrated with life

Reads non-stop and fast

Spelling abilities have been hugely improved

Seems much more confident

Thank You!!!

Kelly O.

When we first came to the practice, my son did not have huge issues, but lots of small ones- trouble with reading, sports (hitting the baseball consistently), coordination, etc- that were not easily detectable,but when put together presented issues. The staff here were all very professional and loving towards him. While I was concerned in the reading, my son was concerned with the athletic side. Seeing improvement night off the bat gave him confidence that i have nor seen in him and made him want to not only Come to therapy, but also made him want to work hard. He has surpassed his grade level and above in reading and hit his first home run this year! Thank you!!!

Alice M.
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