ExpPsy_CogPsy 2024-2025 Lecture 2 PDF

8/30/2024 Chapter 2 Observation Before understanding why people do things, we need to know what they’re actually doing. - Define proper...

8/30/2024 Chapter 2 Observation Before understanding why people do things, we need to know what they’re actually doing. - Define property (of behavior) you wish to observe by means of operational definition (see slide #21) - Detect/measure that property by using a tool/measure that is able to detect the event to which the operational definition refers - A tool/measure should produce the same result whenever it is used to measure the same property. If not: problem with reliability. 30 Chapter 2 Observation Observing the entire population is impossible, so we draw samples to be able to compute an average based on many observations. When the number of observations increase, the sample properties will reflect populations properties more closely. Central tendency: - Mode: most occurring value in sample (N=5: 7,7,7,8,9 mode = 7) - Median: value that splits (the ordered) data-file in two (median = 7) - Mean: arithmetic average (mean = 7.6) How much do observations differ from each other? - Variance and standard deviation BOOK: PAGE 56-57 31 Chapter 2 Observation These values can be used as input for many statistical tests to assess hypotheses. - p-value <.05: We reject H0 and accept H1 Type I error: an observed effect is not real Type II error: an observed null-effect is not real (there actually is an effect) 32 1  8/30/2024 Chapter 2 Observation Bias (tendency to display certain behavior): - Demand characteristics: in an observational setting, people behave in a way that meets expectations or beliefs about desired outcome; participants have beliefs about what the researcher is ‘demanding’ of them. - Students provide high scores on a stress questionnaire because they believe this is what they are supposed to do. - An experiment is entitled “Effects of physical pain on mood” → participants anticipate that they are supposed to feel bad after feeling pain. Observers can also be biased - A coach believes that a track and field athlete is going to be particularly fast today, which can influence the coach’s behavior (shouting louder, providing athlete with convincing pep-talk, etc.) 33 Chapter 2 Explanation Correlation: variations on one variable are synchronized with variations in another variable (variables ‘change together’). - Positive (+1 = perfect positive correlation): variables change in the same direction → time spent studying & exam grade → sunlight hours & leaf growth - Negative (-1 = perfect negative correlation): variables change in opposite directions → age & hearing ability → days in rehab & substance abuse - Uncorrelated: no systematic pattern in variable changes → driving skills & favorite color of shoe laces → length of index finger & money spent on groceries 34 Chapter 2 Explanation strong correlation → weak correlation Negative Positive weak correlation → strong correlation 35 2  8/30/2024 Chapter 2 Explanation Causal relationship: a change in some variable is causing a change in another variable (the cause must precede the effect). Independent variable (X; Cause) Dependent variable (Y; Effect) Food packaging shelf life Amount of water in soil plant growth Wind strength wave height Task difficulty reaction time Hours emersed in combat situation PTSS 36 Chapter 2 Explanation Many variables are correlated, even when relationship seems bizarre: correlation is no evidence for causation (third variable problem). 37 Chapter 2 Explanation Many variables are correlated, even when relationship seems bizarre: correlation is no evidence for causation (third variable problem). 38 3  8/30/2024 Chapter 2 Explanation But how about less bizarre examples? Again: correlation is no evidence for causation. “Television viewing and aggressive behavior were assessed over a 17-year interval in a community sample of 707 individuals. There was a significant association between the amount of time spent watching television during adolescence in early adulthood and the likelihood of subsequent aggressive acts against others”. Science, 2002, Mar 29;295(5564):2468-71 - maybe, watching tv → aggression - maybe, aggressive people simply like to watch more tv (aggression → watching tv) - maybe, watching a lot of tv leads to boredom, and boredom requires people to blow-off steam (tv → boredom → aggression) - maybe, people with lower socioeconomic status (SES) watch more tv, and are more aggressive (SES → tv and aggression) 39 Chapter 2 Explanation But how about less bizarre examples? Again: correlation is no evidence for causation. The Guardian, August 14, 2007 - maybe, obesity → disruption of hormonal balance → infertility - maybe, disruption of hormonal balance → infertility → obesity (negative emotions caused by infertility lead to overeating) - maybe, disruption of hormonal balance leads to both infertility and obesity (hormonal imbalance → infertility & obesity) - maybe, body fat is an effective anti-conceptive - etc. 40 Chapter 2 Explanation But how about less bizarre examples? Again: correlation is no evidence for causation. https://www.all-creatures.org/health/cancerand-bres.html - Causal relationships or not….? Recognize your personal bias and be critical! 41 4  8/30/2024 Chapter 2 Explanation Experimentation: techniques that allow for establishing whether a causal relationship exists Manipulation: creating a pattern of variation in an independent variable (X) to establish changes in Y (dependent variable). Some examples: - Number of words presented (X) in a memory recall test (% of recalled items = Y). - Number of distractors (X) in a visual search task (target localization speed = Y) - Levels of masking noise (X) in a speech recognition task (# of correctly recognized items = Y). Manipulations can be made within-subjects (all participants in an experiment receive 6 levels of masking noise) or between-subjects (i.e., multiple samples are tested → 3 treatment types for anxiety: none, antidepressants, cognitive therapy) 42 Chapter 2 Explanation Example: Does watching tv cause aggressive behavior in children? within-subjects Between-subjects within-subjects measurement manipulation measurement 1) Watch non-violent tv for 2 hours a day (3 weeks) Aggressive behavior 2) Watch violent tv for 2 hours a day (3 weeks) Aggressive behavior 3) Read non-violent books for 2 hours a day (3 weeks) 43 Chapter 2 Explanation Example: Does watching tv cause aggressive behavior? within-subjects Between-subjects within-subjects measurement - If watching tv causes aggressive behavior: manipulation measurement - Increase1)inWatch aggression non-violent(i.e., tv forthe difference 2 hours in aggression a day (3 weeks) measured before/after assigning kids to groups) should be stronger for both tv groups relative to the reading group Aggressive behavior 2) Watch violent tv for 2 hours a day (3 weeks) Aggressive behavior - If watching violent tv causes aggressive behavior: - Increase in aggression (i.e., the difference in aggression measured before/after assigning kids to groups) should be stronger3)for Read non-violent books for 2 hours a day (3 weeks) the violent tv group relative to the non-violent tv and reading group 44 5  8/30/2024 Chapter 2 Explanation Randomization: Assigning participants to a sample is not determined by a third variable; all members of the population of interest have an equal chance to be selected in the sample. A problem in psychology? - WEIRD participants (see Chapter 1, page 35) are not representative of the human race (~16%) - Yet, 96% of samples studied in psychology consist of WEIRD people 45 Chapter 2 Drawing conclusions Internal validity should be sufficient (related to factors within the experiment): The experiment should be designed and carried out in such a way that inferences about causal relationship between X and Y are accurate (related to operationalization, see slide #27). External validity should be sufficient (related to generalizability of the results): The causal relationship between X and Y should be constant across samples, cultures, etc. 46 Chapter 2 Drawing conclusions Validity (measuring what you wish to measure) vs. reliability (consistency of measure) ×× ×× × ×× × × × × × ×× × × × ×× × × × × × valid not valid valid not valid reliable reliable not reliable not reliable 47 6  8/30/2024 Chapter 2 Quantitative/qualitative research Quantitative: measures represent values or counts expressed as numbers (RT, errors, proportion correct [accuracy]). - Systematic scientific investigation in order to quantify phenomena. Qualitative: measures represent assigned names, labels or values (analyzing interviews, personal accounts from an observer). - Detailed insights in individual experiences, understanding, motivation, thoughts, feelings etc. 48 Chapter 3 The human brain Basic organization Two hemispheres connected by the corpus callosum 49 Chapter 3 The human brain Basic organization: White versus grey matter Basic organization: The neuron Dendrites are short and branched in appearance - axons are much longer. In general, dendrites receive signals, and axons transmit them. Most neurons have a lot of dendrites and only have one axon. 50 7  8/30/2024 Chapter 3 The human brain Basic organization Interactive brain model: http://www.brainfacts.org/3D- Brain#intro=false&focus=Brain 51 Chapter 3 Investigating the brain Studying the damaged brain produces valuable insights about its organization Paul Broca (1861): patient with specific damage in left frontal lobe lost ability to produce spoken language, but understanding of speech was intact. Carl Wernicke (1874): patient with specific damage in upper-left temporal lobe had impaired understanding of language, but could produce speech. 52 Chapter 3 Investigating the brain Studying the damaged brain produces valuable insights about its organization Phineas Gage (1848): quiet, conscientious, well- mannered prior to accident, vs. irresponsible, indecisive, irritable, use of profane language after accident Frontal lobe involved in executive functioning (planning, memory, inhibition attention) - A typical example of an executive functioning task: Stroop task Name the color of the text font as quickly as you can BLUE GREEN RED vs. GREEN BLUE RED 53 8  8/30/2024 Chapter 3 Investigating the brain Studying the damaged brain produces valuable insights about its organization Split brain patients: corpus callosum (thick band of nerve fibers that allow hemispheres to communicate) severed Background info on the Visual pathway: right visual field processed in left hemisphere, and vice versa (more later) 54 Chapter 3 Investigating the brain Measuring brain structure Computerized axial tomography (CT scan): multiple X-rays combined into a single image https://www.youtube.com/watch?v=l9s https://nl.wikipedia.org/wiki/ wbAtRRbg Computertomografie 55 Chapter 3 Investigating the brain Measuring brain structure Magnetic Resonance Imaging (MRI): powerful magnet causes charged molecules to re-align to produce field distortions that can be measured. https://www.youtube.com/watch?v=n www.bcbl.eu FkBhUYynUw 56 9  8/30/2024 Chapter 3 Investigating the brain Measuring brain activity Single-cell recordings: activity (action potential, or ‘firing’) of a neuron measured by an electrode - high temporal resolution, precise localization Ludvig et al. (2011) 57 Chapter 3 Investigating the brain Measuring brain activity Electroencephalography (EEG): electrodes on the scalp detect electrical activity (voltage fluctuations resulting from ionic [sodium] currents in the neurons, mostly in pyramidal cells located in the outer layers of the cerebral cortex) – high temporal resolution, relatively poor localization https://www.youtube.com/watch?v=7 Nagel, S. 2019). Towards a home-use BCI: fast asynchronous control and robust non-control state detection. Doctoral 1523EZb8Rg dissertation. Doi: 10.15496/publikation-37739. 58 Chapter 3 Investigating the brain Measuring brain activity Magnetoencephalography (MEG): measures magnetic fields produced by electrical brain activity (i.e., the flow of electrically charged ions through neurons [ionic current flow] produces electromagnetic fields)– high temporal resolution, good localization https://www.youtube.com/watch?v=v www.bcbl.eu JdGIyMA-Pw 59 10  8/30/2024 Chapter 3 Investigating the brain Measuring brain activity functional Magnetic Resonance Imaging (fMRI): activated brain regions need energy which is supplied by blood, fMRI detects changes in blood flow) – relatively poor temporal resolution, good localization https://www.youtube.com/watch?v=n www.bcbl.eu FkBhUYynUw 60 Chapter 3 Investigating the brain Measuring brain activity Positron emission tomography (PET): measure blood flow in the brain via radioactive markers – relatively poor temporal resolution (currently a few seconds at best), good spatial resolution https://www.youtube.com/watch?v=G https://www.olvz.be/nl/pet-centrum-zuidoost- vlaanderen/wat-is-een-pet-scan-zijn-er-risicos HLBcCv4rqk 61 Chapter 3 Investigating the brain Altering brain activity Transcranial magnetic stimulation (TMS): uses magnetic fields to stimulate or inhibit nerve cells (often a therapeutic implementation [TMS can reduce depression]) https://www.youtube.com/watch?v=NQHVfF_5rtc https://brainclinics.com/rtms/ 62 11  8/30/2024 Chapter 3 Investigating the brain Altering brain activity Transcranial direct current stimulation (tDCS): stimulate parts of the brain by applying (low intensity) electrical currents (often a therapeutic implementation) https://neuromtl.com/technolo gy/transcranial-direct-current- https://www.youtube.com/watch?v=Lv1fFcrveqY stimulation-tdcs/ 63 12