Psychophysiological measures
Why use physiological measures?
to study body changes related to mental events
What is psychophysiology?
The discipline that studies changes in the body that are the causes and consequences of mental events.
What is the greatest benefit of physiological measures over neuroimaging?
They are non-restrictive, leading to higher ecological validity
Afferent signals
body to brain
Efferent signals
brain to body
CNS
brain & spinal cord
PNS
nerves & ganglion
Two types of afferent signals
- visceral afferents (smooth muscles of the internal organs)
- somatic afferents (skin, skeletal muscles, tendons, and joints)
What is introception?
The body's internal sensory system that allows us to perceive and process sensations from within our bodies
What are the two systems that go from the brain to the body?
The automatic system
supplies organs, skin, and pupils, modulating resources for survival.
The somatic system
allows the brain to move the body (and face)
also does appetitive and defensive reflexes
What are the two subsystems of the automatic system?
- sympathetic system
fight or flight
- parasympathetic system
rest and digest
often reciprocal systems, but can activate or deactivate at the same time.
Which 5 physiological measures are discussed?
- Cardiac measures
- Electrodermal activity
- Pupil dilation
- Electromyography
- Blushing
How do cardiac measures work?
Electrodes that produce an electrocardiogram, a moment-to-moment recording that is the sum of all electrical activity associated with the beating heart.
What is the influence of the (para) sympathetic system on the heart?
para: decreases heartbeat
symp: increases heartbeat
The application of the parasympathetic brake slows heart rate, while releasing it speeds heart rate. The interplay between these modulatory systems gives rise to heart rate variability (HRV).
What is blood pressure? How do you call high/low blood pressure?
The force exerted against the walls of the blood vessels as blood courses through them.
high pressure (systole) and low pressure (diastole)
How do you mease skin conductance?
Tiny secretions of sweat cause changes in the electrical conductivity of the skin. These changes can be measured with electrodermal activity by passing a very small electrical current between two electrodes, because sweat makes this current flow more easily.
Which system directly influences skin conductance?
The sympathetic system
How do pupils dilate?
Pupil size is controlled by two sets of muscles in the iris:
- Contraction of the sphincter muscle (parasympathetic control) constricts the pupil
- Contraction of the dilator muscle (sympathetic control) widens it.
Constricted pupils are optimised for visual acuity,
Dilated pupils are optimised for visual sensitivity
How to measure muscles?
Electromyography (EMG)
What is the locus coeruleus?
A small, yet crucial, nucleus in the brainstem that plays a significant role in regulating arousal, attention, and the stress response.
Which two factors can you measure for blushing?
Color and temperature
What are the two types of sweat glands?
1. apocrine: mostly located under the armpits and genitalia
2. eccrine: all across the body, mostly on hands and feet
Which neurotransmitter is associated with the sympathetic system?
norepinephrine
Which neurotransmitter is associated with the parasympathetic system?
acetylcholine
4 limitations of physiological measures?
- All functions have a survival function, not meant for indexing states
- Different states can indicate similar responses
- It looks like an objective measure, but it measures subjective states
- It requires the researcher to have knowledge of physiology