Psychology Chapter: Selective Attention and Perception

Selective Attention and Perception

• Selective attention focuses on a limited portion of incoming information, blocking out the rest and shifting focus frequently.
• Inattentional blindness occurs when focused on a task, overlooking other events. Change blindness is a type of inattentional blindness.

Expectations, Context, Motivation, and Emotions in Perception

• Perceptual set is a mental predisposition that filters how we perceive the world.
• Learned concepts (schemas) influence how we organize and interpret ambiguous stimuli.
• Expectations, context, motivation, and emotions shape interpretation of events and behaviors.

Basic Sensory Systems

• Sensory systems:
  • Receive sensory stimulation (often using receptor cells).
  • Transform that stimulation into neural impulses.
  • Deliver neural information to the brain.
  • Transduction is the process of converting one form of energy into another.

Absolute and Difference Thresholds

• Absolute threshold: Minimum stimulation for detecting a stimulus 50% of the time. It varies with individual experience, expectations, and alertness.
• Difference threshold (or just noticeable difference [jnd]):
  • Minimum difference between two stimuli for detection 50% of the time.
  • Weber's Law states the difference must be a constant percentage, not a constant amount, for the difference to be noticeable.

Sensory Adaptation

• Sensory adaptation is the diminished sensitivity to constant stimuli. This allows us to focus on changes in our environment.

Visible Light and the Eye

• Visible light is a small portion of the electromagnetic spectrum, ranging from shorter blue-violet to longer red wavelengths.
• Structures in the eye that help focus light energy:
  • Cornea
  • Pupil
  • Iris
  • Lens
  • Retina
• Wavelength determines hue (color), and amplitude determines intensity (brightness).

Rods and Cones and Information Pathway

• Light triggers chemical changes, converting light energy into neural impulses.
• Photoreceptors (rods and cones) in the retina provide differing sensitivities. Cones to detail and color, rods to faint light and peripheral motion.
• Processed by bipolar and ganglion cells, neural impulses travel from the retina to the thalamus, and then to the visual cortex.

Color Perception

• Young-Helmholtz trichromatic theory proposes three types of color receptors (cones) sensitive to red, green, or blue wavelengths.
• Hering's opponent-process theory proposes three sets of opposing retinal processes (red-green, blue-yellow, white-black), further processing in the retina and thalamus

Feature Detectors

• Specialized nerve cells in the visual cortex.
• Respond to specific features of visual stimuli (shape, angle, movement).
• Pass information to other cortical areas for more complex pattern recognition.

Parallel Processing

• The brain handles multiple aspects of vision simultaneously (color, movement, form, and depth).
• Neural teams integrate these results.
• This enables a holistic understanding of visual perceptions

Sound Characteristics

• Sound waves are bands of compressed and expanded air.
• Our ears detect brief changes in air pressure
• Sound waves differ in amplitude (perceived as loudness) and frequency (perceived as pitch).

How the Ear Transforms Sound

• Middle ear amplifies vibrations from the eardrum to the fluid-filled cochlea.
• Rippling of the basilar membrane causes hair cells to trigger neural messages to the thalamus and auditory cortex.
• Sensorineural hearing loss results from damage to hair cells or the auditory nerve.

Detecting Sound

• Loudness depends on the number of activated hair cells; not the intensity of each response.
• Place theory explains high-pitched sounds, and frequency theory (and volley theory) explains low-pitched sounds.
• The brain analyzes differences in sounds received by both ears to locate the sound source

Touch Sensations

• Four basic touch sensations (pressure, warmth, cold, and pain).
• Combinations produce other sensations (itchy, wet).

Pain

• Biopsychosocial perspective views pain as a combination of biological, psychological, and social-cultural influences.
• Gate-control theory: The spinal cord contains a "gate" that opens to transmit pain signals to the brain, or closes to prevent them.
• Placebos and distraction can control pain by diverting attention and inhibiting pain signals.

Taste and Smell

• Taste (gustation): Six basic sensations (sweet, sour, salty, bitter, umami, oleogustus), combined with aromas.
• Smell (olfaction): 20 million olfactory receptor cells that send messages to the olfactory bulb, temporal lobe's primary smell cortex, and limbic system (for memory and emotion) that allow us to perceive aromas.

Body Position and Movement

• Proprioceptors in muscles, tendons, and joints enable kinesthesis (sense of body position and movement).
• Vestibular sense in the semicircular canals and vestibular sacs senses head tilt and rotation to maintain balance

Sensory Interaction

• Our senses influence each other.
• Sensory interactions can create new perceptions, like the heightened flavoring of a favorite food when you smell it before tasting.

Gestalt Psychology

• Gestalt psychologists studied how the brain organizes fragmented sensory information into wholes, or gestalts.
• Figure-ground and grouping principles (proximity, similarity, closure) guide how we perceive objects.

Perceptual Constancy

• Perceptual constancy allows us to perceive objects as stable despite changing images on the retina. This includes perceiving objects as consistently colored, bright, shaped, and sized, regardless of changing image.

Three-Dimensional Perception

• Depth perception enables us to perceive objects in 3-D, including distances.
• Binocular cues (using both eyes) and monocular cues (using one eye) help us judge distance.

Perceptual Organization and Interpretation

• The brain organizes sensory data into gestalts (whole forms) by using rules like similarity, proximity, closure, continuity

Perception and Adaptation

• Experience guides perceptual interpretations
• Sensory restriction research highlights the critical period for perceptual development (brain's neural organization).
• Perceptual adaptation demonstrates the brain's ability to adjust to constant sensory input (e.g., glasses that shift the world to one side).

Explore the intricacies of selective attention, perception, and sensory systems in this engaging quiz. Understand concepts such as inattentional blindness and the factors that influence how we perceive the world around us. Test your knowledge on thresholds and the brain's processing of sensory information.