AP Psychology: Consciousness, Sleep, and Sensation

Flashcards testing core concepts, empirical studies, biological mechanisms, and sensory systems covered in Modules 1.5 and 1.6 of AP Psychology.

How was consciousness defined at the beginning of psychology's history, and how did its focus change by 1960?

At its beginning, psychology was defined as "the description and explanation of states of consciousness" (Ladd, 1887). By 1960, due to difficulties in scientific measurement and the rise of behaviorism, psychology redefined itself as "the science of behavior," temporarily abandoning the study of consciousness.

How do contemporary psychologists define consciousness?

Contemporary psychologists define consciousness as our subjective awareness of ourselves and our environment.

How does the modern cognitive neuroscience view of the unconscious differ from Sigmund Freud's view?

Sigmund Freud viewed the unconscious as a hiding place for anxiety-provoking ideas and emotions that require uncovering for healing. Modern psychologists view the unconscious track simply as parallel information processing that occurs without awareness.

What is cognitive neuroscience, and what do researchers call the "hard problem"?

Cognitive neuroscience is the interdisciplinary study of brain activity linked with mental processes. The "hard problem" refers to the mystery of how physical brain cells communicating with one another generate subjective conscious awareness.

How did Adrian Owen and colleagues demonstrate conscious awareness in a noncommunicative, unresponsive patient?

Researchers used fMRI scans while asking a 23-year-old unresponsive patient to imagine playing tennis or walking. Her brain exhibited activation patterns in the motor cortex identical to healthy individuals, proving active mental processing.

What neural activity pattern marks the threshold for conscious awareness?

Conscious awareness arises from synchronized, reverberating activity across multiple brain areas (such as language, attention, and memory), whereas weak or subliminal stimuli produce localized sensory activity that quickly fades.

What is the principle of dual processing?

Dual processing is the principle that information is simultaneously processed on two separate tracks: a conscious, deliberate "high road" (reflective and sequential) and an unconscious, automatic "low road" (intuitive and parallel).

What is blindsight, and what does it reveal about human vision?

Blindsight is a condition where a person can respond to visual stimuli without consciously experiencing them. It reveals that vision operates via two separate streams: a visual perception track (conscious recognition) and a visual action track (moment-to-moment guidance of movement).

How do sequential processing and parallel processing differ in function?

Parallel processing is fast and handles routine business simultaneously on multiple unconscious tracks. Sequential processing is slower and is best for solving new problems that require focused, single-target conscious attention.

What is the circadian rhythm, and how does it affect body temperature and alertness?

The circadian rhythm is an internal biological clock roughly synchronized with the 24-hour cycle of day and night. Body temperature rises as morning approaches, peaks during the day, dips in early afternoon, and drops in the evening, with thinking and memory being sharpest near the daily peak.

How do circadian preferences typically shift from early adulthood to older age?

Most 20-year-olds are evening-energized "owls" whose performance improves across the day. After about age $20$, people gradually shift toward being morning-loving "larks."

How was REM sleep discovered in 1952?

Eugene Aserinsky discovered REM sleep while testing an EEG machine on his 8-year-old son, Armond. He observed periods of rapid, jerky eye movements accompanied by high brain activity, during which waking the boy resulted in vivid dream recall.

What brain-wave patterns characterize an alert waking state versus a relaxed waking state?

An alert, waking state is characterized by rapid, low-amplitude beta waves, whereas an awake but relaxed state with eyes closed displays relatively slow, regular alpha waves.

What brain waves and psychological experiences characterize NREM-1 (Stage 1) sleep?

this sleep features slowed breathing and irregular brain waves, and it is often accompanied by hypnagogic sensations or hallucinations, such as the feeling of floating weightlessly or falling.

What EEG feature is characteristic of NREM-2 (Stage 2) sleep?

NREM-2 sleep is characterized by sleep spindles, which are periodic bursts of rapid, rhythmic brain-wave activity that aid in memory processing.

What brain waves characterize NREM-3 (Stage 3) sleep, and what occurs during this stage?

NREM-3 is deep, slow-wave sleep dominated by large, slow delta waves. During this stage, a person is difficult to awaken, bedwetting in children may occur, and the pituitary gland secretes human growth hormone.

Why is REM sleep called "paradoxical sleep"?

REM sleep is called paradoxical sleep because the body is internally aroused (rapid heart rate, irregular breathing, saw-toothed waking-like brain waves, active motor cortex, and genital arousal) yet externally calm, with the brainstem blocking motor messages to produce near-total paralysis.

How does the duration of sleep stages change across a typical night?

Younger adults cycle through sleep stages every $90\,\text{minutes}$. As the night progresses, deep NREM-3 sleep shortens and eventually disappears, while NREM-2 and REM sleep periods become progressively longer.

What is the biological mechanism by which light regulates the sleep-wake cycle?

Light striking retinal proteins signals the suprachiasmatic nucleus (SCN) in the hypothalamus. In response, the SCN directs the pineal gland to suppress production of the sleep-inducing hormone melatonin, whereas darkness causes the SCN to quiet down, increasing melatonin release.

What are the six evolutionary and physiological functions proposed for sleep?

Sleep functions to: (1) protect from danger in an ecological niche, (2) restore body tissues and prune toxic waste/neurons, (3) consolidate memories, (4) feed creative thinking, (5) support physical growth via human growth hormone release, and (6) conserve metabolic energy.

According to William Dement, how long does the brain keep track of accumulated sleep debt?

The brain keeps an accurate count of accumulated sleep debt for at least two weeks.

What hormonal changes caused by sleep deprivation contribute to weight gain?

Sleep deprivation increases ghrelin (hunger-arousing hormone), decreases leptin (hunger-suppressing hormone), and increases cortisol (stress hormone stimulating fat production), while decreasing overall metabolic rate.

What is insomnia, and why are sleeping pills and alcohol contraindicated as long-term treatments?

Insomnia is the persistent difficulty in falling or staying asleep. Sleeping pills and alcohol aggravate insomnia over time by suppressing REM sleep, impairing daytime memory and concentration, and leading to tolerance.

What are the primary characteristics of narcolepsy and sleep apnea?

Narcolepsy involves sudden, uncontrollable attacks of overwhelming sleepiness lasting under $5\,\text{minutes}$, sometimes collapsing directly into REM sleep. Sleep apnea is characterized by repeatedly stopping breathing during sleep, resulting in brief awakenings, slow-wave sleep deprivation, and daytime fatigue.

How does sleepwalking (somnambulism) differ from REM sleep behavior disorder?

Sleepwalking occurs during NREM-3 deep sleep and involves walking or complex motor acts with no dream recall. REM sleep behavior disorder occurs during REM sleep and results from a failure of the normal motor paralysis, causing individuals to act out, punch, or kick according to their vivid dreams.

How did Sigmund Freud distinguish between the manifest content and latent content of dreams?

Freud identified manifest content as the remembered, symbolic storyline of a dream, and latent content as the underlying, unconscious drives, wishes, and erotic conflicts that would be threatening if expressed directly.

What does the activation-synthesis theory propose about the origin of dreams?

The activation-synthesis theory proposes that dreams are the brain's attempt to synthesize and make sense of random neural static originating from the brainstem, which is emotionally shaped by the limbic system while frontal lobe inhibitions idle.

What is REM rebound?

REM rebound is the tendency for REM sleep duration to increase significantly following periods of REM sleep deprivation once an individual is allowed to sleep undisturbed.

What is the difference between bottom-up processing and top-down processing?

Bottom-up processing begins at sensory receptors and works up to higher levels of brain processing to detect raw features. Top-down processing constructs perceptions by filtering incoming sensory input through experience, expectations, and context.

What are the three fundamental steps basic to all sensory systems?

All sensory systems: (1) receive sensory stimulation, often using specialized receptor cells; (2) transform that stimulation into neural impulses (transduction); and (3) deliver the neural information to the brain.

What is an absolute threshold, and who pioneered its study?

Pioneered by Gustav Fechner, the absolute threshold is the minimum stimulus energy needed to detect a particular stimulus $50\%$ of the time.

What does signal detection theory state regarding the detection of faint stimuli?

Signal detection theory posits that detecting a faint stimulus (signal) amid background stimulation (noise) depends not only on the stimulus's strength but also on an individual's psychological state, including experience, expectations, motivation, and alertness.

What is Weber's law, and what are its constant percentage thresholds for light, weight, and tone frequency?

Weber's law states that for an average person to perceive a difference, two stimuli must differ by a constant minimum percentage rather than a constant amount. The percentages are: light intensity by $8\%$, object weight by $2\%$, and tone frequency by $0.3\%$.

What is sensory adaptation, and why don't static objects vanish when we stare at them?

Sensory adaptation is reduced sensitivity resulting from constant, unchanging stimulation, occurring because nerve cells fire less frequently. Objects do not vanish from vision because our eyes continuously jump (saccades) roughly every third of a second, continually shifting retinal stimulation.

How do the physical properties of light waves correspond to sensory experiences?

A light wave's wavelength (peak-to-peak distance) determines its hue (perceived color). A wave's amplitude (height) determines its intensity, which governs perceived brightness.

What is accommodation in the human eye?

Accommodation is the process by which the eye's transparent lens changes its curvature and thickness to focus light rays reflected from near or far objects onto the retina.

What are the structural and functional differences between rods and cones?

Cones (approx. $6\,\text{million}$) are concentrated in the central fovea, have direct individual hotlines to bipolar cells, and detect fine detail and color in bright light. Rods (approx. $120\,\text{million}$) are located in the retinal periphery, share bipolar cells in clusters, and provide black-and-white vision, motion detection, and high sensitivity in dim light.

What causes the blind spot in the human eye?

The blind spot is caused by the absence of photoreceptor cells (rods and cones) where the optic nerve leaves the back of the eyeball.

What is the sequence of neural transmission from the retina to the visual cortex?

Light triggers photochemical changes in rods and cones $\to$ activates bipolar cells $\to$ activates ganglion cells (whose axons form the optic nerve) $\to$ crosses the optic chiasm $\to$ relays through the thalamus $\to$ arrives at the visual cortex in the occipital lobe.

How does the Young-Helmholtz trichromatic theory explain color vision?

The Young-Helmholtz trichromatic theory states that the retina contains three distinct types of color-receptor cones, each maximally sensitive to one of three primary wavelengths of light: red, green, or blue. Perception of all other colors comes from combining these three signals.

How does Ewald Hering's opponent-process theory explain negative afterimages?

Opponent-process theory states that color vision is processed through opposing retinal and thalamic channels: red-green, yellow-blue, and white-black. Staring at green tires the green receptor response; when switching gaze to white paper (which reflects all wavelengths), only the unopposed red response fires normally, producing a red afterimage.

What are feature detectors, and who discovered them?

Discovered by David Hubel and Torsten Wiesel, feature detectors are specialized neurons in the visual cortex of the occipital lobe that respond selectively to specific visual features, such as edges, lines, angles, and movement.

Where is the fusiform face area located, and what condition results from its impairment?

The fusiform face area is located on the underside of the right temporal lobe. Damage to this area results in prosopagnosia (face blindness), where individuals cannot recognize familiar human faces despite having normal vision.

How does parallel processing enable visual perception?

Parallel processing allows the brain to simultaneously analyze multiple distinct visual subdimensions—motion, form, depth, and color—integrating them across neural teams to construct a unified perception.

How do the physical properties of sound waves determine loudness and pitch?

A sound wave's amplitude (wave height) determines its perceived loudness. A sound wave's frequency (wavelength; measured in hertz) determines the perceived pitch: long waves have low frequency/pitch, and short waves have high frequency/pitch.

What is the structural pathway of sound through the ear during auditory transduction?

Sound waves vibrate the eardrum $\to$ middle ear bones (hammer/malleus, anvil/incus, stirrup/stapes) amplify vibrations $\to$ oval window of cochlea vibrates $\to$ cochlear fluid ripples the basilar membrane $\to$ cilia on hair cells bend $\to$ neural impulses travel along the auditory nerve $\to$ thalamus $\to$ auditory cortex in the temporal lobe.

How does sensorineural hearing loss differ from conduction hearing loss?

Sensorineural hearing loss (nerve deafness) is caused by damage to the cochlea's hair cell receptors or the auditory nerve. Conduction hearing loss is caused by damage to the mechanical system (eardrum or middle ear ossicles) that transmits sound waves to the cochlea.

How does the brain differentiate between loud and soft sounds?

The brain interprets loudness from the total number of activated hair cells, not from the intensity of an individual hair cell's response.

How do place theory and frequency theory together explain pitch perception?

Place theory explains high pitches: sound waves trigger vibrations at specific places along the cochlea's basilar membrane. Frequency theory explains low pitches: the rate of nerve impulses matches the frequency of the sound wave, with volley theory explaining frequencies above $1000\,\text{waves/second}$ via alternating neural firing.

How does the auditory system localize sound sources in space?

The brain computes a sound's location by detecting minute differences in the arrival time (as small as $0.000027\,\text{second}$) and relative intensity of sound waves striking one ear compared to the other.

What four basic skin sensations combine to create all tactile experiences?

Touch is a mixture of four basic and distinct skin senses: pressure, warmth, cold, and pain. Combinations of these produce other sensations, such as tickle (adjacent pressure spots), itch (repeated pain stimulation), wetness (cold and pressure), and heat (cold and warmth).

What is the gate-control theory of pain, and how can the "gate" be closed?

Proposed by Melzack and Wall, gate-control theory states that the spinal cord contains a neurological gate. Small nerve fibers conduct pain signals and open the gate, while large-fiber activity (massage, electrical stimulation, acupuncture) or descending brain signals (distraction, endorphin release) close the gate to block pain.

How does psychological memory editing influence how people evaluate past pain?

People overlook the total duration of an experience and instead recall pain based on two factors: the peak moment of intensity and the amount of pain felt at the very end.

What are the six basic taste sensations and their respective survival indications?

The six basic tastes are: sweet (energy source), salty (sodium essential for physiology), sour (potentially toxic acids), bitter (potential poisons), umami (proteins for tissue growth/repair), and oleogustus (fats for energy, insulation, and cell growth).

Why does the olfactory system bypass the thalamus?

Olfaction is an evolutionary primitive sense whose receptor axons run directly from the nasal cavities to the olfactory bulb and onward to the olfactory cortex in the temporal lobe and limbic system (hippocampus/amygdala), bypassing the brain's main sensory relay switchboard (thalamus).

How does the human olfactory system discriminate up to 1 trillion different scents with only about 350 receptor types?

Linda Buck and Richard Axel discovered that odor molecules bind to combinations of receptors in distinct patterns, which the olfactory cortex interprets like letters of the alphabet combining to form different words.

What is kinesthesis, and what sensory receptors make it possible?

Kinesthesis is the sense of the position and movement of individual body parts, enabled by proprioceptors located in muscles, tendons, and joints that continuously feed information to the brain.

What anatomical structures in the inner ear are responsible for the vestibular sense?

The vestibular sense relies on the fluid-filled semicircular canals (which look like a three-dimensional pretzel) and the calcium-crystal-filled vestibular sacs, which stimulate hair-like cilia that send balance signals to the cerebellum.

What is the McGurk effect, and what does it demonstrate about sensory interaction?

The McGurk effect occurs when an individual sees a speaker mouth one syllable (such as "ga") while hearing another syllable (such as "ba"), leading the brain to blend the two into a third perception (such as "da"). It demonstrates that vision and audition dynamically interact to determine speech perception.

What is embodied cognition, and how does it affect judgments?

Embodied cognition is the influence of bodily sensations, gestures, and physical states on cognitive preferences and judgments (e.g., sitting in a hard chair leads people to administer harsher penalties for crimes than sitting in a soft chair).

What is synesthesia?

Synesthesia is a condition where the stimulation of one sensory pathway leads to automatic, involuntary experiences in a second, distinct sensory pathway (such as hearing a musical pitch and seeing a specific color).