Sensory process & perception Eesha Sharma, MD

Sense organs

Receptor potential Generator potential

Psychophysics Gustav Theodor Fechner, 1860 Quantitative relationship between physical stimuli and the sensations and perceptions they effect – Subject’s experience or behavior Objectively measurable stimuli – Absolute thresholds – Discrimination thresholds – Scaling

Experience SensationPerceptionApperception

Perceptual processes Attention Form perception Visual depth perception Constancy Movement perception Plasticity Individual differences

Attention The perceptual process that selects certain inputs for inclusion in our conscious experience, or awareness, at any given time

Filtering Parallel processing Serial processing Processing capacity

Form perception Recognition of a figure on a ground

Contours

Organization Gestalt: The whole is more than the sum of its parts Laws of perceptual organization – Proximity – Similarity – Symmetry or good figure – Continuation – Closure

Visual depth perception Monocular cues – Linear perspective – Clearness – Interposition – Shadows – Gradients of texture – Movement Binocular cues – Retinal disparity

Constancy Size constancy – Results when the object and its background change together in such a way that the relationship between them stays the same – Moon in the night sky Brightness constancy – Result of unchanged brightness ratios

Movement perception Real motion perception – Constancy: because of unchanged relationship between object and its background – The brain comparator Apparent motion – Stroboscopic motion – Autokinetic effect – Induced movement

Plasticity Visual deprivation – Sensitive period – Nature and nurture

Individual differences Perceptual learning – An increase in the ability to extract information from the environment as a result of experience or practice with the stimulation coming from it – Ornithologists; Blind people Set – Readiness or priming for certain kinds of sensory input Motives and needs – Rorschach inkblots Perceptual-cognitive style – Flexibility – Field dependence