Chap 3 - PSYC 213 Book Notes Chapter 3 Synaesthesia confusing the senses Mixing of senses in the brain Stimulation of one sense simultaneously produces

Chap 3 - PSYC 213 Book Notes Chapter 3 Synaesthesia...

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PSYC 213 Book Notes Chapter 3 Synaesthesia: confusing the senses - Mixing of senses in the brain Stimulation of one sense simultaneously produces another sensation in a different modality - Different forms Ex : grapheme-color synaesthesia : seeing certain numbers or letters as certain colors - Can you learn to be a synesthe? Experiment: Colizoli 2016: 16 non-synesthete participants task: read books with certain letters printed in certain colors (> 1000 000 words) results: subjectively reported ‘synaesthesia’: ‘i am experiencing color when thinking about certain letters” problems with this study: no control group! A common misunderstanding - when we see, there is input into the eye - extramission belief: when we see,t here is a ray that exits the eye onto an object (an output; false) The Visual System Early visual processing: Sensation Eyes and the optic nerve 1. Light waves inter the eye, focused onto the retina (a thin layer of tissue at back of eye) 2. Photoreceptors in the retina convert light to electrical activity Rods: low light level; night vision Cones: high light level; detail 3. The electrical signal is sent to bipolar cells and then to ganglion cells 4. Signal exits through the optic nerve to the brain - Info is compressed: millions of photoreceptors in each retina converge into 100x fewer ganglion cells optic nerve brain - Cells are non-uniformly distributed Most cones are in fovea (small area in centre of visual field) so more detailed vision here More rods on outside of fovea peripheral vision is less detailed bottom line: perception is contructive + perceiving is not just seeing
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Early to later visual processing - Optic nerve - Each eye’s optic nerve transmits info to both hem Left visual field perceived via right hem and vice versa contralaterality: opposite site Later visual processing: Perception Visual cortex (occipital lobe) - Primary Visual Cortex: specialized regions of cells that process particular visual attributes or features Edges, angles, color, light, size, motion, dimensions - Visual Association Area: interprets info acquired through PVC assigns meaning to what we see - Processing streams: the what (ventrla) and where (dorsal) pathways - Neuroimaging studies: object identification VS spatial location tasks activate the what and where pathways Lessons from the visual system - We don’t sense or perceive info directly - Visual stimuli is latered/ ‘broken apart’ in the processing pipeline (compression + functional specialization in PVC) - These pieces of info are integrated back together to be interpreted as a whole perceiveing = constructing Visual agnosia: an inability to identify objects visually even though they can be identified using other senses (ex: touch) Basic sensory systems are intact, not blindess Visual association areas are damaged - Dissociation between being able to see visual features and interpreting those visual features problems assigning meaning - Can be selective to particular types of processing there are cases of selective deficits in visual recognition Propospagnosia
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