Psych Week 9

Sensation

The process by which our sense organs and sensory receptors receive raw physical or chemical energy from the natural outside world.

Transduction

The process of converting raw physical or chemical energy from the environment into neural signals that the brain can understand.

Perception

The cognitive process where the brain actively interprets, organizes, and gives meaning to transduced neural signals.

Three Brain Lobes for Sensing

The occipital, temporal, and frontal lobes of the cerebral cortex that work together to process and sense the world.

Psychophysics

The scientific study of the relationship between physical stimuli in the outside world and our psychological perception of them.

Absolute Threshold

The minimum amount of physical stimulation required to detect a particular stimulus 50% of the time.

Just Noticeable Difference (JND)

The minimum difference between two stimuli required for a person to detect a change 50% of the time.

Weber's Law

The psychophysical principle stating that to be perceived as different, two stimuli must differ by a constant minimum percentage rather than a constant amount.

Signal Detection Theory

A theory predicting how and when we detect the presence of a faint stimulus amid background noise, depending on experience, expectations, motivation, and alertness.

Sensory Adaptation

Diminished sensitivity to a constant, unchanging stimulus over time, allowing attention to focus on informative changes in the environment.

Subliminal Perception

The processing and detection of stimuli that fall below a person's conscious absolute threshold for awareness.

Electromagnetic Radiation

The spectrum of light energy waves that the human eye detects to produce vision.

Wavelength (Vision)

The distance from one wave peak to the next, which determines the perceived hue or color of light.

Amplitude (Vision)

The height of a light wave, which determines the perceived intensity or brightness of the light.

Pupil, Lens, and Vitreous Humor

The pathway structures light travels through as it enters the eye and is focused onto the back surface of the retina, projecting images upside-down and left-right reversed.

Retina

The light-sensitive inner surface at the back of the eye where visual transduction occurs within specialized photoreceptor cells called rods and cones.

Rods

Specialized retinal photoreceptors for dim light and peripheral vision that detect black, white, and gray, enabling night vision.

Dark Adaptation

The gradual adjustment and increased sensitivity of rods and cones when moving from a brightly lit environment into darkness.

Cones

Specialized retinal photoreceptors concentrated near the center of the retina that function in bright light and process fine detail and color vision via three types (red, blue, and green).

Bipolar Cells

The second cellular layer of the retina that receives chemical signals from rods and cones and processes basic information regarding angles, lines, and edges.

Ganglion Cells

The third cellular layer of the retina that performs opponent-process color functions and whose axons bundle together to form the optic nerve.

Optic Nerve

The bundle of ganglion cell axons that carries transduced visual neural messages from the eye through the thalamus to the visual cortex in the occipital lobes.

Trichromatic Theory of Color Vision

The theory stating that the retina contains three distinct types of color receptors (cones) sensitive to red, green, and blue, which combine to produce any visible color.

Opponent-Process Theory

The theory stating that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision, explaining afterimages because some cells are stimulated by one color and inhibited by its pair.

Frequency (Hearing)

The number of complete sound wavelengths that pass a point per second, which determines the perceived pitch of a sound.

Amplitude (Hearing)

The height or physical intensity of a sound wave, which determines the perceived loudness of a sound.

Cochlea and Basilar Membrane

The coiled, fluid-filled tube in the inner ear containing the basilar membrane lined with specialized cilia (hair cells), where auditory transduction converts sound vibrations into neural signals.

Auditory Pathway to the Brain

Transduced sound signals travel from the hair cells on the basilar membrane along the auditory nerve through the thalamus to the auditory cortex in the temporal lobes.

Place Theory of Hearing

The theory that links the pitch we hear with the specific place where the cochlea's basilar membrane is stimulated, best explaining how we hear high-pitched sounds.

Frequency Theory of Hearing

The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, enabling us to sense pitch, best explaining low-pitched sounds.

Gustation (Taste)

The chemical sense where molecules dissolved in saliva stimulate specialized receptor cells (taste buds) located inside the tongue's papillae, sending signals along a cranial nerve through the thalamus to the cortex.

Olfaction (Smell)

The chemical sense where airborne molecules dissolve in the nose's mucous membranes to stimulate olfactory receptor cells, sending signals via the olfactory bulb directly to the temporal lobe and limbic system.

Olfactory Pathway Exception

The crucial anatomical rule that olfactory (smell) neural messages bypass the thalamus completely, traveling straight to the olfactory bulb, temporal lobes, and limbic system.

Somatic Sense (Touch)

The skin sense detecting pressure intensity via specialized pressure receptor cells in the skin, sending neural messages along cranial or spinal nerves through the thalamus to the somatosensory cortex in the parietal lobes.

Temperature Sense

The skin sense detecting thermal changes via specialized warm and cold receptor cells in the skin, traveling via spinal nerves through the thalamus to the parietal lobes and interacting with touch sensations.

Pain Sense

The protective sense detecting tissue injury or damage via specialized pain receptors in the skin, sending signals along spinal nerves through the thalamus to the somatosensory cortex in the parietal lobes.

Vestibular Sense

The sense of balance, body position, and movement relative to gravity, transduced by cilia (hair cells) in the ear's semicircular canals and sent along the auditory nerve to several brain regions including the cerebellum.

Kinesthetic Sense

The sense of body part position and movement, transduced by specialized proprioceptors located in the joints, tendons, and muscles, sending signals via spinal nerves through the thalamus to the parietal lobes.