Lesson 4: Comprehensive Study Notes on Sensation, Perception, and Visual Processing

Vocabulary flashcards covering sensory thresholds, subliminal perception, attention, eye anatomy, visual pathways, and theories of color vision.

Sensation

The activation of receptors located in various organs.

Perception

The method by which sensations are organized and interpreted.

Subliminal messages

Sensory stimuli presented below the level of conscious perception of their presence.

Silverman's Study on Depression

A visual subliminal study on individuals diagnosed with depression, where words flashed behind neutral scenes served as the independent variable and reported depressed symptoms served as the dependent variable.

Greenwald's Study on Subliminal Audio Tapes

A study conducted on college students where the independent variable was what participants were told about the content of the tapes, and the dependent variable was their self-reported memory and self-esteem.

General Characteristics of Subliminal Effects

Principles establishing that visual subliminal stimuli are more likely to produce an effect than auditory stimuli, they push individuals in the direction of feelings they already possess rather than changing them, and their effects are short-lived.

Backmasking

A recorded message, often embedded in songs, that has no meaning unless played in reverse.

Absolute threshold

The weakest stimulation of a sense that is detected $50\%$ of the time when presented as a single stimulus.

Just noticeable difference (JND)

The smallest difference or change between multiple stimuli that is perceived $50\%$ of the time.

Weber's law

The principle stating that the just noticeable difference (JND) is always a constant percentage change rather than a constant amount change.

Habituation

A cognitive process where the brain stops attending to constant, unchanging auditory stimuli.

Sensory Adaptation

A physiological process where sensory receptors become less responsive over time when exposed to constant, non-auditory sensory stimuli.

Selective attention

Focusing perceptual awareness on specific aspects of the environment while ignoring others.

Change blindness (Inattention Bias)

The failure to detect important changes in the visual environment when attention is engaged elsewhere in a task.

Rods

Vastly outnumber cones and are localized primarily in the peripheral regions of the retina. They have low spatial acuity, do not register color, and are specialized for scotopic vision (low-light, dim, and nocturnal illumination).

Cones

Densely packed within the central fovea region of the retina. They mediate high-resolution visual acuity, process color vision, and are specialized for photopic vision (high-intensity, bright daylight conditions).

Ventral stream

The pathway in visual processing that carries a flow of visual information identifying 'what' is being viewed in the visual field.

Dorsal stream

The pathway in visual processing that carries a flow of visual information identifying 'where' an object is located.

Amplitude (Brightness)

The physical dimension of light waves corresponding to perceived brightness, ranging from dim light to bright light.

Wavelength (Color)

The physical property of light waves determining hue, where longer waves produce red light and shorter waves produce blue light.

Subtractive coloring

The process of removing wavelengths of light being reflected from a surface, such as occurs when mixing colored paints.

Additive coloring

The process of increasing the wavelengths of light being reflected from a surface, such as occurs when mixing colored lights.

Young and Helmholtz trichromatic theory

A theory stating that color vision is based on three photopigments (red, green, blue), explaining color processing at the retinal level rather than the cortical level.

Karl E. Hering's opponent processing theory

A theory proposing that color is arranged in specific antagonistic pairs, thought to explain color processing in the brain at the cortical level.

Retina

The retina is the light-sensitive inner neural lining at the back of the eye containing specialized photoreceptive cells. Visual signals travel from photoreceptors through bipolar neurons to ganglion cells (whose axons form the optic nerve).

Photoreceptors

are specialized light-sensitive cells located within the retina at the posterior lining of the eye. They serve as the foundational cells for vision by converting light waves into neural signals.