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

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

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