• Wilhelm Wundt established the first psychological laboratory in Germany in 1879, and studied the basic elements of mental experience.
• Early researchers defined psychology as “the science of mental life.”
• This definition was revised under the influence of the behaviorists in the 1920s to the “scientific study of observable behavior.”
• In the 1960s, the humanistic psychologists and the cognitive psychologists revived interest in the study of mental processes.
• Psychology is now defined as “the science of behavior and mental processes.”

• Psychology's current perspectives include neuroscience, evolutionary, behavior genetics, psychodynamic, behavioral, cognitive, and social-cultural.
• Psychology's subfields include biological, developmental, cognitive, personality, social, counseling, health, clinical, and industrial-organizational.
• Psychologists may conduct basic research to increase the field’s knowledge base or applied research to solve practical problems.

• Critical thinking is smart thinking. It challenges our beliefs and triggers new ways of thinking.
• Behavior is a biopsychosocial event. The biological, psychological, and social-cultural levels of analysis each offer valuable insight into behavior and mental processes.
• We operate with a two-track mind (dual processing). Our brains process a surprising amount without our awareness, which affects our perception, thinking, memory, and attitudes.
• Psychology explores human strengths (positive psychology) as well as challenges (clinical psychology).

• Hindsight bias (the I-knew-it-all-along phenomenon) is believing, after learning the outcome, that we would have foreseen it.
• Overconfidence is the human tendency to be more confident than correct.
• We perceive order in random events due to our natural eagerness to make sense of our world.
• These tendencies lead us to overestimate our intuition and common sense, and then come to the wrong conclusion.

• Curiosity triggers new ideas.
• Skepticism encourages attention to the facts.
• Humility helps us discard predictions that can’t be verified by research.

The scientific attitude carries into life as critical thinking, which puts ideas to the test by examining assumptions, uncovering hidden values, weighing evidence, and assessing conclusions.

• Psychological theories are explanations using principles that organize observations and predict behaviors or events.
• Theories generate hypotheses—predictions that can be tested using descriptive, correlational, or experimental methods.
• Research results may validate the theory, or lead to its rejection or revision.
• The precise language used in operational definitions allows replication by others. If others achieve similar results, confidence in the conclusion will be greater.

• Case studies study one person or group in depth, in the hope of revealing things true to us all.
• Naturalistic observation studies examine behavior in naturally occurring situations without trying to change or control the situation.
• Surveys study many people in less depth, using random sampling to fairly represent the population being studied.

• In a positive correlation, both items increase or decrease together.
• In a negative correlation, one item increases as the other decreases.
• Correlations tell us how well one event predicts another (using a measure called a correlation coefficient), but not whether one event caused the other, or whether some third factor influenced both events.

• Experiments create a controlled, simplified version of reality to discover cause-effect relationships.
• Psychologists manipulate one factor (the independent variable) while controlling others.
• The researchers can then measure changes in other factors (dependent variables).
• Experiments minimize confounding variables, such preexisting differences between groups (through random assignment).
• Experiments allow researchers to compare experimental group results with control group results.
• Experiments may use a double-blind procedure to control for the placebo effect.

• Studying specific examples in controlled environments can reveal important general principles. The general principles that result, not the specific findings, help explain everyday behaviors.

• Research on animals advances our understanding of other species and sometimes benefits them directly.
• Animal experimentation advances our understanding of ourselves and may help solve human problems.
• Professional ethical standards and other legal guidelines, enforced by ethics committees, protect participants.
• The APA ethics code outlines standards for safeguarding human participants’ well-being, including obtaining their informed consent and debriefing them later.

• Psychologists’ values influence their choice of research topics, their theories and observations, their labels for behavior, and their professional advice.
• Psychology’s principles could be used for good or evil, but have been used mainly to enlighten and to achieve positive ends.

• The testing effect shows that learning and memory are enhanced by actively retrieving, rather than simply rereading, previously studied material.
• The SQ3R study method—survey, question, read, retrieve, and review—applies principles derived from memory research and can help you learn and remember material.
• Four additional study tips are
  (1) distribute your study time;
  (2) learn to think critically;
  (3) process class information actively; and
  (4) overlearn.