09/01/2025
Visual
Information
Processing
LECTUR E 1: P SYC 1059
Dr Nayant ara Ramamoo r thy
n.ramamo or thy @gre.ac.uk
1
Lecture outline
Part 1
• Sensation & Perception
• The Visual system
Part 2
• Visual Information Processing
• Errors in perception – illusions
• Virtual Reality
2
Sensation
and
Perception
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09/01/2025
Key concepts
Stimulus: any piece of
sensory information
Sensation: the process by
which physical properties
of the stimulus are
converted to neural
signals
Perception: the
organisation and
interpretation of
incoming sensory input
Visual Information Processing
Sensation
Dr Nayantara Ramamoorthy
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Key concepts
Percept: basic unit
of perceptual
representation
Flow of perceptual information
High-level
representation
Can you describe
the Cutty Sark
DLR station?
Top-down
processing
transformation 3
Representation C
We can apply an
informationprocessing
approach to the
study of perception
Bottom-up
processing
transformation 2
Representation B
transformation 1
Perceptual
processing can occur
in two directions:
• Bottom-up
• Top-down
Representation A
Input
Adapted from Gilhooly, Lyddy & Pollick (2014)
Visual Information Processing
Perception
Dr Nayantara Ramamoorthy
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Key concepts
Bottom-up processing:
information from the
stimulus flows in a series
of feed-forward
transformations
Flow of perceptual information
shape?
colour?
High-level
representation
Top-down
processing
transformation 3
Representation C
Bottom-up
processing
transformation 2
Representation B
Top-down processing:
higher-level information
can exert an influence on
lower-level processes in a
feedback manner
?
transformation 1
Representation A
Input
Adapted from Gilhooly, Lyddy & Pollick (2014)
Perception
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Visual Information Processing
Dr Nayantara Ramamoorthy
09/01/2025
The visual system
“Painting outside Painting”, Tamara Špitaler Škorić, Saatchi Art
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How your eyes work - link to source video
Visual System
Visual Information Processing
Dr Nayantara Ramamoorthy
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Visual Information
Processing
“Infinity Mirror Room”, Yayoi Kusama, Tate
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09/01/2025
Parietal lobe
Occipital lobe
Temporal lobe
Visual Information Processing
Visual Information Processing
Dr Nayantara Ramamoorthy
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Key concepts
Rod cells: photoreceptor
cells that work in dim
light conditions
Kauffmann, Ramanoël, & Peyrin, (2014)
Cone cells: photoreceptor
cells that work in bright
light conditions
Magnocellular pathway:
receives information from
rod cells (and connects to
parietal lobe)
Magnocellular (M) pathway
Parvocellular (P) pathway
Parvocellular pathway:
receives information from
cone cells (and connects
to inferotemporal lobe)
Visual Information Processing
Visual Information Processing
Dr Nayantara Ramamoorthy
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Key concepts
Dee had deficits in the
ability to process the
form or shape of objects
(visual agnosia)
Dee could still perform
appropriate actions on
objects she could not
perceive
Goodale & Milner
studied Dee’s visual
difficulties – their
research led to a change
in how visual information
processing is understood
Visual Information Processing
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Visual Information Processing
Dr Nayantara Ramamoorthy
09/01/2025
Two-stream hypothesis
VISION FOR ACTION
Posterior Parietal Cortex
V3/V4
Pulvinar
SC
Area V1
LGN
Retina
Amygdala
Inferotemporal Cortex
VISION FOR PERCEPTION
Goodale & Milner (1992, 2008); Milner (2017)
Visual Information Processing
Visual Information Processing
Dr Nayantara Ramamoorthy
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Key concepts
Two streams of
processing are fairly
independent of each
other
Dorsal stream  bottom-up processing  direct or ecological view
Dorsal stream:
responsible for
determining where
objects are in the visual
field (vision for action)
Ventral stream:
responsible for object
recognition and
identification (vision for
perception)
Ventral stream  top-down processing  constructivist view
Visual Information Processing
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Perceptual Illusions
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Visual Information Processing
Dr Nayantara Ramamoorthy
09/01/2025
Key concepts
Pre-attentive processing:
occurs before attention is
directed to a stimulus
Principles of perceptual
organisation laid out by
Gestalt psychology
Optical illusions work by
exploiting assumptions of
perceptual organisation
Perceptual Illusions
Visual Information Processing
Dr Nayantara Ramamoorthy
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Key concepts
Phantom limb
phenomenon: brain
generates pain
information that does not
exist in a physical sense
This phenomenon has
also been generated in
non-amputee individuals
(“rubber hand illusion”)
Brain regions involved:
posterior parietal cortex
(vision for action) and
temporo-parietal junction
Perceptual Illusions
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Virtual Reality
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Abdulkarim, Hayatou, & Ehrsson, (2021)
Visual Information Processing
Dr Nayantara Ramamoorthy
09/01/2025
Fulvio et al. (2020)
Ortiz-Catalan et al. (2016)
Visual Information Processing
Virtual Reality
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Summary
• Cognitive psychology  the mind as an information processor
• Cognitive neuroscience  underlying neural correlates of cognitive processes
• Perception  constructs an experience of world around us (and can be error-prone)
• Visual information processing  two-stream model
• Virtual Reality  clinical application
Visual Information Processing
Dr Nayantara Ramamoorthy
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References
Fulvio, J. M., Ji, M., Thompson, L., Rosenberg, A., & Rokers, B. (2020). Cue-dependent effects of VR experience on motion-in-depth sensitivity. PLoS One, 15(3), e0229929.
Goodale, M. A., & Milner, A. D. (1992). Separate visual pathways for perception and action. Trends in neurosciences, 15(1), 20-25.
Kauffmann, L., Ramanoël, S., & Peyrin, C. (2014). The neural bases of spatial frequency processing during scene perception. Frontiers in integrative neuroscience, 8, 37.
Milner, A. D. (2017). How do the two visual streams interact with each other?. Experimental brain research, 235(5), 1297-1308.
Milner, A. D., & Goodale, M. A. (2008). Two visual systems re-viewed. Neuropsychologia, 46(3), 774-785.
Ortiz-Catalan, M., Guðmundsdóttir, R. A., Kristoffersen, M. B., Zepeda-Echavarria, A., Caine-Winterberger, K., Kulbacka-Ortiz, K., ... & Hermansson, L. (2016). Phantom
motor execution facilitated by machine learning and augmented reality as treatment for phantom limb pain: a single group, clinical trial in patients with chronic intractable
phantom limb pain. The Lancet, 388(10062), 2885-2894.
Illusion of the year: https://illusionoftheyear.com/
Required reading: Eysenck & Keane (2020). Cognitive Psychology: Chapter 2
Additional reading: Gilhooly, Lyddy, & Pollick (2014). Cognitive Psychology: Chapters 1 and 2
Visual Information Processing
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