PSYCH 104- Midterm 2 Notes

Genes and Evolution

Evolution

Evolution is defined as the change in heritable traits within a population over extended periods. It is driven by various mechanisms, with natural selection being the most significant, whereby individuals with traits that are better suited to their environment are more likely to survive and reproduce.

Natural Selection

Natural selection is the process through which advantageous traits become more common in successive generations. Factors such as competition for resources, environmental changes, and predation pressures contribute to this selective process.

Behavior

Behavior refers to how organisms respond to various stimuli in their environment. For instance, a human may put on a toque when they feel cold, demonstrating a behavioral response likely influenced by both genetics and environmental conditions.

Genes and Their Functions

Genes

Genes are fundamental units of heredity that encode specific traits and are inherited from one or both parents. They consist of sequences of DNA that play crucial roles in determining physical characteristics and biological functions.

Alleles

Wild-type allele: This represents the original, unmutated form of a gene, which typically expresses the most common phenotype.
Mutant allele: This is a modified form of a gene that may result in alternative phenotypic expressions, which can manifest as different traits.

Non-coding DNA

Non-coding DNA constitutes segments of DNA that do not encode proteins but have essential regulatory roles, influencing the expression of coding genes and maintaining genome structure.

Genotype vs. Phenotype

Genotype: The genetic constitution of an individual, encompassing all the alleles inherited.
Phenotype: The observable traits or characteristics of an organism, which emerge from the interaction between genotype and environmental factors.

Gene Function and Expression

Translation & Transcription

These are fundamental processes through which genetic information is converted into proteins. Transcription is the first step where the DNA sequence of a gene is transcribed into messenger RNA (mRNA). Subsequently, translation occurs where the mRNA is used as a template for synthesizing proteins.

Polygenic Transmission

Polygenic transmission refers to scenarios where multiple genes collectively influence a single trait, resulting in a range of phenotypic outcomes, such as height or skin color.

Epigenetics

Epigenetics examines heritable changes in gene expression that do not involve changes to the underlying DNA sequence. These changes can be influenced by environmental factors, lifestyle choices, and experiences, leading to variations in how traits are expressed.

Recombinant DNA Procedure

Recombinant DNA technology involves inserting a gene from one organism into the genome of another organism, allowing for the production of genetically modified organisms (GMOs) with desired traits.

Gene Knockout Procedure

The gene knockout procedure intentionally disables a specific gene to study its function and effects on the organism, helping researchers understand the role of genes in various biological processes.

Behavior Genetics

Behavior genetics is the field that explores the interplay between genetic predispositions and environmental influences on behavior and personality traits.

Heritability

Heritability is a measure of the extent to which genetic factors account for observable variations in a trait within a population, as opposed to environmental influences.

Concordance Rates

Concordance rates indicate the likelihood that both twins will exhibit the same characteristic, providing insights into the genetic influence on specific traits, particularly in twin studies.

Reaction Range

The reaction range concept suggests that the environment can significantly influence the expression of genetic potential, leading to varied phenotypes even among individuals with the same genotype.

Evolutionary Psychology

Evolutionary psychology investigates how human behavior and cognition adapt over time due to natural selection, aiming to explain modern behaviors through the lens of evolutionary survival mechanisms.

Natural Selection & Adaptations

Natural selection leads to adaptations, which are traits that enhance an organism's chances of survival and reproduction in a specific environment.

Social Adaptations

Social adaptations facilitate interactions among individuals within species, promoting cooperative behaviors such as language development and social bonding—essential for group survival.

Mating Systems & Parental Investment

Parental Investment

Parental investment refers to the resources (time, energy, and care) that parents allocate to nurture their offspring, significantly affecting offspring survival rates and future reproductive success.

Mating Systems

Monogamous: A mating system where one male pairs with one female for a breeding season or for life.
Polygamous: A system involving multiple reproductive partners.
- Polygyny: A specific type where one male mates with multiple females.
- Polyandry: Where one female mates with multiple males, often resulting in shared parental care among mates.

Mate Preferences

Males: Typically prefer females exhibiting signs of health and the likelihood of parental investment, impacting reproductive outcomes.
Females: Often prioritize youth and physical attractiveness in mates, as these traits are associated with fertility and good genes.

Cooperation and Altruism

Cooperation

Cooperative behaviors involve individuals assisting others while also gaining benefits themselves, which can strengthen social bonds and improve group survival.

Altruism

Altruism is characterized by selfless acts performed for the benefit of others, often at a personal cost. Kin selection is a key mechanism driving altruistic behaviors, as individuals are more likely to assist relatives to ensure the continuation of shared genetic traits.

Sensation and Perception

Sensation

Sensation encompasses the processes wherein sensory receptors detect external stimuli, serving as the first step in the perception process.

Perception

Perception is the mental organization and interpretation of sensory information, allowing individuals to make sense of their environment.

Transduction

Transduction refers to the transformation of sensory input into neural signals that the brain can understand, which is crucial for effective perception.

Thresholds

Absolute Threshold: The minimal intensity of a stimulus needed for detection by the sensory system.
Difference Threshold: The smallest change in stimulus intensity that produces a noticeable difference in sensation, an essential aspect of sensory discrimination.

Auditory and Visual Systems

Sound Waves

Sound waves are vibrations that travel through different media, characterized by properties such as frequency (pitch) and amplitude (loudness).

Human Ear Components

The ear consists of three main parts:

Outer Ear: Collects sound waves.
Middle Ear: Contains ossicles which transmit sound.
Inner Ear: Houses the cochlea, which converts sound vibrations into neural signals transmitted to the brain.

Visual System Properties

Light behaves as both a wave and a particle, traveling through space and interacting with objects, exhibiting properties such as amplitude (brightness) and wavelength (color).

Color Perception

Additive Color Mixing

This occurs when different colors of light are combined, resulting in new colors produced by the addition of wavelengths.

Subtractive Color Mixing

In contrast, subtractive mixing involves the removal of wavelengths from light, which is how pigments appear differently when mixed.

Trichromatic Theory

According to this theory, three types of cone cells in the retina are responsible for color detection, each sensitive to red, green, or blue light wavelengths, forming the basis for color vision.

Consciousness

Consciousness entails the awareness of both internal mental processes and external stimuli, influencing behavior and thought.

Attention

Attention is the cognitive process that allows individuals to focus on specific stimuli while simultaneously disregarding others, playing a critical role in perception and awareness.

Sleep Stages

Sleep consists of distinct cycles characterized by varying physiological patterns, with rapid eye movement (REM) sleep being crucial for cognitive function and emotional health.

Dreaming and Altered States

Dream Theories

Numerous theories aim to explain the significance and purpose of dreams, including Freud's theory of wish fulfillment and the Activation-Synthesis theory, which views dreams as the brain's attempt to interpret random neural activity.

Hypnosis and Meditation

These techniques are employed to alter consciousness, enhance focus, and promote relaxation, having applications in both therapeutic and personal development contexts.

Psychoactive Drugs

Psychoactive substances are chemicals that induce changes in brain function, leading to alterations in perception, mood, or behavior. Their effects vary widely and are often classified as stimulants, depressants, or hallucinogens, each with distinct mechanisms of action.