Measuring The Mind Flashcards
Quantitative psychology
- Contrast with qualitative psychology. Records rather than measures.
- In quantitative psychology we try to quantify behaviour and experiences.
How do we quantify behaviour and experiences?
Subjective measures
- Likert scale
- Labelled levels
- Odd number
- Bimodal
- Anchored scales (Numeric scales)
- Only endpoints are labelled
- Limited number of responses
How much are you enjoying this lecture?
1 2 3 4 5 6 7 8 9
Not at all A lot
- Visual Analogue Scale (VAS)
- Only endpoints are labelled
Distance to anchors is measured
Getting objective
- Does a behaviour happen or not?
- Is unused paper recycled or discarded?
Accuracy point of subjective equivalence (PSE)
accuracy of detection can change across a range of stimuli values
2-alternative-forced-choice (2afc)
- Accuracy of 2afc decision reveals.
Chance level is at 50% performance
Accuaracy
discrimination and criterion
different criteria are being employed in the two situations but your ability to discriminate remains the same.
Every decision can be seen in
Signal Detection Theory
- Hearing a tone in a noisy background.
- Detecting a bomb in luggage x-ray.
- Deciding whether to release a missile.
- Deciding whether a PCR Covid test is really an infection or not.
Deciding whether to approach an attractive person (reading the signals).
look at diagrams in notes
SDT Outcome
- From proportions of Hits and False alarms SDT will give you Discrimination (d’) and Criterion (β).
- Discrimination is how easy the task is (how overlapping the curves are).
- Criterion is the level that the participant is using to make the decision (conservative or liberal).
- You can do the calculation online at:
- https://elvers.us/perception/sdtCalculator/
It is all about timing…
* Some tasks take longer than others
* 5 + 5 = ?
* 27 x 13 = ?
* One word to complete these three words
* ________ jack, _________board, _________ hole.
Longer tasks take more stages of processing
Measuring the speed of mental processes
- Herman von Helmholtz
- Frog legs experiment.
Neural impulses travel at 100km/hr
mental processes from reaction times
Donders 1968 method of subtraction
IF task B includes all elements of task A plus some additional element the time required to do that additional element with be the difference between the reaction times of the two tasks
light —> light detection —> response —> simple RT
light —> light detection —-> discrimination (red/green) —> response —> Goho-go RT
Sternberg’s 1969 addictive factors logic
if two different changes to a task effect the task in an addictive way, then the two changes affect different stages of processing. if they are interactive, then they affect the same task.
graphs in notes
visual search and reaction times
reaction times used to identify visual feature pop outs. features are unaffected by search size.
graphs in notes
combining accuracy and reaction data. drift diffusion model
graph in notes
Insight into the mind from other measures
- Heart rate – Linked to arousal
- Heart rate variability – Linked to stress
- Blood pressure – Linked to stress and anxiety
- Galvanic skin response – Linked to arousal and recognition
○ Fluid increases in sweat ducts increasing skin conductance - Electromyography (EMG) – Directly records muscle activity
○ Electrodes placed over the muscle locations - Hormone levels
○ Cortisol, Testosterone.
○ Measures taken from saliva or urine - Eye tracking
○ Able to identify regions of interest and measure time spent looking at those regions and number of saccades to those regions. - Pupil dilation
Used to measure arousal.
Other methods to investigate brain function
-fMRI
-MEG/EEG
fMRI
- Functional magnetic resonance
imaging- Measures blood oxygen levels in the brain as an indicator of regional activity (BOLD)
- High spatial resolution (voxels of less than 1mm)
- Records in 3D (ie, internal brain activity)
- Disadvantages
- Indirect measure of brain activity
Slow responses (2-5s) makes temporal resolution poor
- Indirect measure of brain activity
MEG/EEG
- Magnetoencephalography
- Electroencephalography
- Measurement of electrical action potentials at the scalp to infer synaptic activity.
- High temporal resolution (better than 1ms)
- Disadvantages
Poorer spatial localisation
Event Related Potentials (ERPs)
- Take a particular event and measure the pattern of potentials following it.
- Repeat many times.
Find the average pattern for a particular type of event - These are many of the tools that we have to try to uncover the inner workings of the mind.
- They provide us with the data that help build models of how stimuli produce behaviours.
- There is one last way to find out what is in someone’s mind.
- Just ask them.
That is what happens in qualitative research.
summary
- To understand the mind, we need to code observable responses.
- These responses come in many formats
- Subjective
- Objective binary responses
- Reaction times
- Physiological responses
- Neuropsychological responses
Which one is appropriate depends on the question that we are asking
terms
- Likert scale, Anchored scale, VAS
- PSE, 2afc, JND
- SDT, Discrimination (d’), and Criterion (β)
- Reaction times/Response times
- Donders, Sternberg, Visual search
- Physiological responses
- GSR, EMG, Heart Rate…
- fMRI
MEG/EEG
who to measure - sampling procedures
those ptps constitute a sample which may be considered a subset of some general group called the population. the eventual goal of research in psychology is to draw conclusions that apply to some general population.
probability sampling
each member of the population has a definable probability of being selected for a sample. its commonly used in survey research when researchers have better access to their target population of interest from which they want to take a sample. the sample needs to reflect the attributes of the target population as a whole. when this happens the sample is representative. if it doesn’t happen the simple is biased. the sample needs to be selected using a clearly define sampling procedure.
random sampling
the simplest form of probability sampling is to take a simple random sample. this means each member of the population has an equal chance of being selected as a member of the sample. the procedure usually involves software that uses a random number generator or table. simple random sampling is often an effective, practical way to create a representative sample.
It is sometimes the method of choice for ethical reasons as well. In situations in which only a small group can receive some benefit or must incur some cost, and there is no other reasonable basis for decision‐making, random sampling is the fairest method to use. There are two problems with simple random sampling. First, there may be systematic features of the population you might like to have reflected in your sample. Second, the procedure may not be practical if the population is extremely large.
stratified sampling
In a stratified sample, the proportions of important subgroups in the population are represented precisely. In the previous example, with a goal of a sample of 100, 60 women would be randomly sampled from the list of female students, and 40 men would be randomly selected from the list of male students.
it doesn’t solve the problem of trying to sample from a large population when it is often impossible to acquire a complete list of individuals.
cluster sampling
Cluster sampling, a procedure frequently used by national polling organizations, solves the problem. With this approach, the researcher randomly selects a cluster of people all having some feature in common. A campus survey at a large university might be done this way. If a researcher wanted a cross section of students and stratified sampling was not feasible, an alternative would be to get a list of required ‘core’ classes. Each class would be a cluster and would include students from a variety of majors. If 40 core classes were being offered, the researcher might randomly select 10 of them and then administer the survey to all students in each of the selected classes. If the selected clusters are too large, the researcher can sample a smaller cluster within the larger one.