What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception
Research in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus – ground tru...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2015-04-01
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| Series: | Frontiers in Human Neuroscience |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fnhum.2015.00205/full |
| _version_ | 1819168337091887104 |
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| author | Barbara eBlakeslee Mark E McCourt |
| author_facet | Barbara eBlakeslee Mark E McCourt |
| author_sort | Barbara eBlakeslee |
| collection | DOAJ |
| description | Research in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus – ground truth). It is agreed that the visual system must compare different regions of the visual image to solve this inverse problem; however, the nature of the comparisons and the mechanisms underlying them are topics of intense debate. Perceptual illusions are of value because they reveal important information about these visual processing mechanisms. We propose a framework for lightness research that resolves confusions and paradoxes in the literature, and provides insight into the mechanisms the visual system employs to tackle the inverse problem. The main idea is that much of the debate and confusion in the literature stems from the fact that lightness, defined as apparent reflectance, is underspecified and refers to three different types of judgments that are not comparable. Under stimulus conditions containing a visible illumination component, such as a shadow boundary, observers can distinguish and match three independent dimensions of achromatic experience: apparent intensity (brightness), apparent local intensity ratio (brightness-contrast), and apparent reflectance (lightness). In the absence of a visible illumination boundary, however, achromatic vision reduces to two dimensions and, depending on stimulus conditions and observer instructions, judgments of lightness are identical to judgments of brightness or brightness-contrast. Furthermore, because lightness judgments are based on different information under different conditions, they can differ greatly in their degree of difficulty and in their accuracy. This may, in part, explain the large variability in lightness constancy across studies. |
| first_indexed | 2024-12-22T19:02:00Z |
| format | Article |
| id | doaj.art-89a4d068f89647d89fc44be8b7e6cf82 |
| institution | Directory Open Access Journal |
| issn | 1662-5161 |
| language | English |
| last_indexed | 2024-12-22T19:02:00Z |
| publishDate | 2015-04-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj.art-89a4d068f89647d89fc44be8b7e6cf822022-12-21T18:15:54ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612015-04-01910.3389/fnhum.2015.00205118264What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perceptionBarbara eBlakeslee0Mark E McCourt1North Dakota State UniversityNorth Dakota State UniversityResearch in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus – ground truth). It is agreed that the visual system must compare different regions of the visual image to solve this inverse problem; however, the nature of the comparisons and the mechanisms underlying them are topics of intense debate. Perceptual illusions are of value because they reveal important information about these visual processing mechanisms. We propose a framework for lightness research that resolves confusions and paradoxes in the literature, and provides insight into the mechanisms the visual system employs to tackle the inverse problem. The main idea is that much of the debate and confusion in the literature stems from the fact that lightness, defined as apparent reflectance, is underspecified and refers to three different types of judgments that are not comparable. Under stimulus conditions containing a visible illumination component, such as a shadow boundary, observers can distinguish and match three independent dimensions of achromatic experience: apparent intensity (brightness), apparent local intensity ratio (brightness-contrast), and apparent reflectance (lightness). In the absence of a visible illumination boundary, however, achromatic vision reduces to two dimensions and, depending on stimulus conditions and observer instructions, judgments of lightness are identical to judgments of brightness or brightness-contrast. Furthermore, because lightness judgments are based on different information under different conditions, they can differ greatly in their degree of difficulty and in their accuracy. This may, in part, explain the large variability in lightness constancy across studies.http://journal.frontiersin.org/Journal/10.3389/fnhum.2015.00205/fullcontrastlightnessbrightnessAchromatic Perceptioninferred-lightness |
| spellingShingle | Barbara eBlakeslee Mark E McCourt What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception Frontiers in Human Neuroscience contrast lightness brightness Achromatic Perception inferred-lightness |
| title | What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| title_full | What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| title_fullStr | What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| title_full_unstemmed | What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| title_short | What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| title_sort | what visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception |
| topic | contrast lightness brightness Achromatic Perception inferred-lightness |
| url | http://journal.frontiersin.org/Journal/10.3389/fnhum.2015.00205/full |
| work_keys_str_mv | AT barbaraeblakeslee whatvisualillusionstellusaboutunderlyingneuralmechanismsandobserverstrategiesfortacklingtheinverseproblemofachromaticperception AT markemccourt whatvisualillusionstellusaboutunderlyingneuralmechanismsandobserverstrategiesfortacklingtheinverseproblemofachromaticperception |