Everything AP psych 1-2 unit

Experimental research

the only type of research that can establish a definitive cause-and-effect relationship

Independent Variable

The factor that the researcher intentionally manipulates or changes

Dependent Variable

The factor being measured to see if it responds to changes in the IV

Example: In a study testing if caffeine affects memory, the amount of caffeine is the IV, and the score on the memory test is the DV

Confounding Variables

Any outside factors other than the IV that could impact the outcome or skew the results of the DV

Random Assignment

Participants must be randomly sorted into either the experimental group (receives treatment) or the control group (does not receive treatment). This acts as a critical control mechanism to limit confounding variables

Hypothesis

A researcher's prediction about the relationship between variables. It must be falsifiable (possible to be proven wrong through objective testing)

Quantitative

Uses numerical value systems, like Likert scales (e.g., rating something from 1 to 5)

Qualitative

Explores descriptions, such as structured interviews with open-ended responses

Correlation

Measures the relationship between two variables. It cannot prove causation

Expressed as a correlation coefficient between -1.00 and +1.00.

Positive Correlation

Both variables move in the same direction

Negative Correlation:

Variables move in opposite directions

Zero Correlation:

No relationship exists. The closer the coefficient is to -1 or +1, the stronger the relationship is

Meta-Analysis:

A statistical approach that pools together the findings of multiple independent studies on the same topic to establish a single, broader conclusion

Naturalistic Observation

Observing and recording behaviors in a real-world setting without any researcher interference or manipulation

Sampling Bias:

Occurs if the process of selecting a sample group is flawed, meaning some members of the target population are given a higher chance of selection than others

Generalizability

If a sample does not accurately represent the broader population, the findings of the study cannot be generalized to the public

Institutional Review Board (IRB):

An ethics board that must evaluate and approve any proposed study before it begins to ensure compliance with safety standards

Informed Consent

Participants must be fully informed about the nature of the study and explicitly agree to take part

Informed assent

When dealing with minors, researchers must obtain informed assent from the child in addition to parental consent

Measures of Central Tendency:

Mean (average), median (middle score), and mode (most frequent score).

Range

The absolute difference between the highest and lowest scores in a data set

Standard Deviation:

Measures how clustered or spread out data points are from the mean. A small standard deviation indicates scores sit close to the mean; a large standard deviation means they are widely scattered

The Normal Curve:

A symmetrical, bell-shaped distribution where the mean, median, and mode all align precisely at the center point

Effect Size:

Measures the strength of a relationship (in non-experimental studies) or the magnitude of difference between groups (in experiments). Typically, .2 is small, .3 to .7 is medium, and .8 or higher is large

Statistical Significance

A calculation indicating that the results of a study are highly unlikely to be the product of random chance, meaning the independent variable truly caused the observed change

Twin & Adoption Studies:

Frequently leveraged by behavioral geneticists to investigate how nature (genetics) versus nurture (environment) shapes individual differences and traits

Evolutionary Perspective:

Examines behavioral and mental processes through the lens of natural selection, exploring how certain adaptive traits are passed down because they increased our ancestors' survival odds

Historical Misuse (Eugenics):

eugenics—the problematic belief in controlling human reproduction to selectively breed for "desirable" traits while discouraging reproduction among those with traits deemed "undesirable"

The Neuron:

The fundamental building block of the nervous system. You must understand how neural transmission works:

• the process by which nerve cells (neurons) communicate with each other. It uses a combination of electrical signals within a single neuron and chemical messengers to bridge the gap between neighboring cells, controlling everything from movement and thought to emotion.

Dendrites

• Receive incoming chemical messages (neurotransmitters) from other neurons.

Axon

• The long extension that carries an electrical impulse (action potential) away from the cell body toward the axon terminals

Myelin Sheath:

A fatty layer covering the axon that insulates it and dramatically speeds up the transmission of electrical signals.

Axon Terminals & Synapse:

The end of the neuron where chemical neurotransmitters are released across the synaptic gap to communicate with neighboring cells.

Action Potential:

A brief electrical charge that travels down an axon. It is an all-or-none response, meaning a neuron either fires completely or it doesn't fire at all.

Reuptake

After neurotransmitters are released into the synapse and bind to receptor sites, the sending neuron reabsorbs the excess neurotransmitters.

Serotonin

Regulates mood, sleep, hunger, and arousal. (Undersupply is linked to depression).

Dopamine

Influences movement, learning, attention, and emotion. (Oversupply linked to schizophrenia; undersupply linked to Parkinson's disease).

Endorphins

• Natural, opiate-like neurotransmitters linked to pain control and pleasure.

Neuroplasticity

The brain's ability to reorganize itself, form new neural connections, and adapt in response to learning, experience, or following an injury.

The Brainstem:

Responsible for automatic survival functions (e.g., the Medulla controls heartbeat and breathing).

The Limbic System:

Associated with emotions and drives:

Amygdala

Linked to fear, aggression, and emotional processing.

Hippocampus

Crucial for processing and forming new explicit memories.

Hypothalamus

Directs eating, drinking, body temperature regulation, and governs the endocrine system via the pituitary gland.

The Cerebral Cortex:

The intricate fabric of interconnected neural cells covering the cerebral hemispheres: Frontal Lobes and Occipital Lobes

Frontal Lobes:

Involved in speaking, muscle movements, making plans, and judgment.

Occipital Lobes:

Include areas that receive and process visual information.

EEG (Electroencephalogram):

Records electrical activity across the brain's surface (excellent for sleep studies).

fMRI (Functional Magnetic Resonance Imaging):

Tracks blood flow to show real-time brain activity and functioning during specific tasks.

PET Scan (Positron Emission Tomography):

Tracks a radioactive form of glucose to detect where brain activity is highest during a task.

Sensation vs. Perception:

Sensation is the process by which our sensory receptors receive stimulus energies from our environment. Perception is the process of organizing and interpreting that sensory information.

Transduction:

The process of converting physical energy (like light waves or sound waves) into neural impulses that the brain can interpret.

Bottom-Up Processing:

Sensory analysis that begins at the entry level, starting with the raw sensory receptors and working up to the brain's integration.

Top-Down Processing:

Information processing guided by higher-level mental processes, drawing on our expectations, experiences, and context.

Absolute Threshold:

The minimum stimulation needed to detect a particular stimulus (like a light or sound) 50% of the time.

Difference Threshold

(Just Noticeable Difference): The minimum difference between two stimuli required for detection 50% of the time. Governed by Weber's Law, which states that two stimuli must differ by a constant minimum percentage (rather than a constant amount) to be perceived as different.

Weber’s Law:

To perceive a difference between two stimuli, they must differ by a constant minimum percentage rather than a fixed physical amount.

• Example: If you add 1 ounce to a 10-ounce weight, you will notice the difference. If you add 1 ounce to a 100-ounce weight, you will not detect it because the percentage change is too small.

Signal Detection Theory

Predicts how and when we detect the presence of a faint stimulus ("signal") amid background stimulation ("noise"). It emphasizes that detection depends not just on the strength of the signal, but also on our psychological state—our experience, expectations, motivation, and alertness level.

Sensory Adaptation:

Diminished sensitivity to a stimulus as a consequence of constant, unchanging exposure.

• Example: Walking into a room and noticing a strong odor, but after a few minutes, you completely stop smelling it because your sensory receptors fire less frequently.

Light Characteristics:

* Wavelength (distance between peaks): Determines the hue or color we perceive.

• Amplitude (height of the wave): Determines the intensity or brightness of the color.

Anatomy of the Eye:

• Cornea: Clear protective outer layer that bends light to help focus it.

• Pupil: The adjustable opening in the center of the eye through which light enters.

• Iris: A ring of muscle tissue that forms the colored portion of the eye and controls the size of the pupil opening.

• Lens: The transparent structure behind the pupil that changes shape (accommodation) to help focus images on the retina.

• Retina: The light-sensitive inner surface of the eye containing the receptor cells (Rods and Cones) that begin the process of transduction.

Cornea

Clear protective outer layer that bends light to help focus it.

Pupil:

The adjustable opening in the center of the eye through which light enters

Iris:

A ring of muscle tissue that forms the colored portion of the eye and controls the size of the pupil opening.

Lens:

The transparent structure behind the pupil that changes shape (accommodation) to help focus images on the retina.

Retina:

The light-sensitive inner surface of the eye containing the receptor cells (Rods and Cones) that begin the process of transduction.

Rods:

Photoreceptors

Detect black, white, and gray; necessary for peripheral and twilight/night vision. Located on the outer edges of the retina.

Cones:

Photoreceptors

Detect fine detail and give rise to color sensations. Concentrated near the center of the retina, specifically in the fovea (the area of sharpest focus).

Visual Path to the Brain:

Rods and cones activate Bipolar Cells, which then activate Ganglion Cells. The axons of the ganglion cells bundle together to form the Optic Nerve, which carries the neural impulses to the Thalamus, routing them finally to the Visual Cortex in the occipital lobe.

Trichromatic Theory

(Young-Helmholtz): The retina contains three different types of color receptors—one most sensitive to red, one to green, and one to blue. When stimulated in combination, they can produce the perception of any color.

Opponent-Process Theory:

Visual information is analyzed in terms of opponent colors processed by receptor pairs: red-green, yellow-blue, and white-black. This theory perfectly explains the phenomenon of afterimages (e.g., staring at a green square and seeing a red silhouette when looking away at a white wall).

Sound Characteristics:

* Frequency (wavelength length): Determines the pitch (highness or lowness of a sound).

• Amplitude: Determines the loudness (measured in decibels).

Outer Ear:

Collects sound waves via the pinna and channels them down the auditory canal to the eardrum (tympanic membrane).

Middle Ear:

Concentrates the vibrations of the eardrum through three tiny bones: the hammer, anvil, and stirrup (ossicles), transmitting them to the oval window of the cochlea.

Inner Ear:

Contains the Cochlea, a snail-shaped, fluid-filled tube. Sound waves vibrating the fluid cause ripples in the basilar membrane, which bends the microscopic hair cells lining its surface. Bending these hair cells triggers nerve impulses that travel via the auditory nerve to the Auditory Cortex in the temporal lobe.

Circadian Rhythm:

Our internal biological clock that operates on a roughly 24-hour cycle, regulating patterns of alertness, body temperature, and hormone release.

Suprachiasmatic Nucleus (SCN):

A pair of cell clusters in the hypothalamus that controls the circadian rhythm. In response to morning light, the SCN causes the brain’s pineal gland to decrease its production of the sleep-inducing hormone melatonin. In the dark, it triggers an increase in melatonin to cause drowsiness.

The Stages of Sleep

Throughout the night, our brain cycles through distinct stages roughly every 90 minutes:

NREM-1 (Stage 1)

The transition stage between wakefulness and sleep. Marked by slow alpha waves shifting to theta waves. Individuals may experience hypnagogic sensations (vivid dream-like hallucinations or sudden jerking falling sensations).

NREM-2 (Stage 2):

Periodic bursts of rapid, rhythmic brain-wave activity called sleep spindles and large single spikes known as K-complexes. This is the stage where we spend the majority of our total sleep time.

NREM-3 (Stage 3):

Deep sleep. Characterized by large, slow delta waves. It is incredibly difficult to awaken someone in this stage. This is when sleepwalking, sleeptalking, and night terrors typically occur.

REM Sleep (Rapid Eye Movement):

A paradoxical stage of sleep. The brain waves mimic an awake, alert state (beta-like waves), heart rate rises, and breathing becomes rapid. However, the motor cortex is blocked, resulting in sleep paralysis (muscles are completely relaxed). This is the stage where vivid, story-like dreaming occurs.

Figure-Ground:

The organization of the visual field into objects (the figure) that stand out from their surroundings (the ground).

Closure

We automatically fill in gaps to create a complete, whole object.

Binocular Cues:

Depth cues that rely on the use of both eyes.

Retinal Disparity:

The brain calculates distance by comparing the slightly different images received by your left and right retinas. The greater the difference (disparity) between the two images, the closer the object is.

Convergence:

A neuromuscular cue caused by the inward turning of the eyes when focusing on a nearby object.

Monocular Cues:

Depth cues available to either eye alone.

Norepinephrine:

Helps control alertness and physical arousal during fight-or-flight moments.

GABA (Gamma-Aminobutyric Acid):

The primary inhibitory neurotransmitter (quiets down brain activity).

Glutamate:

The primary excitatory neurotransmitter involved in memory and cognitive function.

Central Nervous System (CNS):

Composed strictly of the Brain and the Spinal Cord. It acts as the primary command center.

Peripheral Nervous System (PNS):

Sensory and motor neurons connecting the central nervous system to the rest of the body.

Somatic Nervous System:

Controls the body’s skeletal muscles and oversees voluntary movements.

Autonomic Nervous System (ANS):

Controls involuntary, automatic functions of our internal organs and glands (like heartbeat or digestion).

Sympathetic Nervous System:

Alarms, enlivens, and mobilizes the body for action during stressful situations (Fight-or-Flight; accelerates heart rate, dilates pupils, inhibits digestion).

Parasympathetic Nervous System:

Calms the body down after stress has passed, conserving its physical resources (Rest-and-Digest; slows heart rate, stimulates digestion).