Perceptual organization

Perceptual organization • How do we form meaningful perceptions from sensory information?

Gestalt psychology • Branch of cognitive psychology • Organization of many sensations into perceptions of wholes • Gestalt = whole or form • Based on experience and expectations • Perceived whole is not always the same as its parts!

Form perception • Simplification into easily interpretable wholes • Figure-ground

Form perception • Grouping principles • Proximity • Similarity • Continuity • Connectedness • Closure

Depth perception • Distance is perceived with vision and hearing • Visual depth perception • Binocular cues • Monocular cues

Binocular depth cues • Retinal disparity • Strongest visual depth cue

Monocular depth cues • Light and shadow • Relative size and position • Relative height/vertical position • Linear perspective

Auditory location cues • Intensity and pitch • Arrival times at each ear • Clarity

Perceptual constancy • Cognitive functions that maintain the features of an object, despite changing illumination, color, size, or shape • Based on comparisons between the figure and ground

Color and lightness constancy • Consistent color and light intensity, despite changes in illumination

Shape and size constancy • Familiar objects are perceived as unchanging despite changes in retinal images.

Perceptual interpretation • Making sense of the perceptions produced by the cortex • Genetics • Experience • Critical periods • Plasticity and adaptation

Perceptual set • Psychological predisposition to perceive stimuli in a particular way • Shaped by learned assumptions and beliefs • Affects how we interpret sensory stimuli • Examples

Other sensory modalities

Hearing • Stimulus - sound waves • Frequency • Amplitude

The ear

Auditory stimuli • Bending of hair cells in the cochlea transduces vibrations into neural signals • Auditory nerve • Primary auditory cortex • Auditory association cortex

Touch • Stimulus - pressure, pain, warmth, cold • Receptors • Other sensations • Stimuli organized in primary somatosensory cortex • Perceptions created in somatosensory association cortex

Pain • Critical alert system • Subjective • Physiology • Prior experiences • Attention • Context • Culture

Pain • Gate-control theory • Pain control/management

Salty Sweet Sour Bitter Umami Taste • Stimulus - chemical molecules that impart the sensations of sweet, sour, salty, bitter and umami • Tastebuds contain taste and touch receptors

Taste perception • Flavor • Based on taste, olfactory, and touch stimuli • Begins in brainstem • Completed in the limbic system

Taste preferences • Genetic predisposition • Biological predisposition • Learned responses

Smell • Stimulus - chemical molecules • Receptors in olfactory epithelium • Axons project directly to the olfactory bulb of the brain • Perception begins in the olfactory bulb, completed in the limbic system

Kinesthesis & vestibular sense • Kinesthesis - sense of body position and movement • Vestibular sense - sense of head postion and movement • Stimulus - gravity and movement • Receptors found in muscles (body) and inner ear (head)

Kinesthesis & vestibular sense • Sensory signals about position and movement are organized in the medulla and cerebellum • Perception occurs throughout the brain • Brain stem • Temporal cortex

Perceptual organization