Lecture 6: Physiological Sensing Flashcards
Why should we use physiologial sensing in HCI?
List some pros and cons of physiological sensing
Briefly define “Biological signals”
Biological signals are space, time, or space-time records of a biological event such as a beating heart or a contracting muscle. The electrical, chemical, and mechanical activity that occurs during this biological event often produces signals that can be measured and analyzed
Name physiological sources for the bio
signals “Bioelectric Signals”, “Electrical conductance” and “Bioimpedance signals”
Name physiological sources for the bio
signals “Biomagnetic Signals”, “Biomechanical Signals” and “Biochemical Signals”
Name physiological sources for the bio
signals “Bioacoustic Signals” and “Biooptical Signals”.
List some tools/approaches to measure biological signals
Bio Potential (ECG, EMG, EEG)
Physical Measurements (Displacement, Air flow, temperature)
Blood gas sensors (blood- oxygen, pH, carbon monoxide)
Bio analytical sensors
Optical sensors
How can we classify Signal Acquisition?
Invasive: placement of sensor inside the body
Non-Invasive: On the body, e.g. surface electrodes
Active: external stimuli, e.g. emitting a signal and measuring response
Passive: without external stimuli
Describe the orign of the signals, measured by: EMG, ECG, EOG, EEG, EP/RP.
EMG: electrical signals generated by muscles
ECG: electrical signals that originate from the activity of the human heart
EOG: electrical signals from the change of the cornea-retinal potential due to eye movement
EEG: electrical signals from the brain measured on the scalp with a multichannel data-acquisition device
EP/RP (evoked potential/event related potential): electrical signals as response of the brain to external stimuli. (e.g., viusal stimuli)
Describe the major components in acquiring signals
What are the major steps in signal analysis?
- Amplification
- Filtering
- Digitization
- (Transmission)
- Processing
- Transmission / Storage
Sketch the stages of biosignal processing
Define “Psychophysiology”
Measurement of physiological responses as a proxy for mental activity and behavior.
What is the difference between Physiology & Psychophysiology?
Human physiology seeks to understand the mechanisms that work to keep the human body alive and functioning.
Human psychophysiology seeks to understand the mechanisms that work to keep the human mind conscious and functioning.
Name a example for the classical systems view:
- knee-jerk reflex: input is mechanical force and output is mechanical motion
- pupillary light reflex: light is the input and output is mechanical change in iris muscles
What are fundamental challenges of the psychophysiology computing?
- Psychophysiological inference
- Psychophysiological validity
- The representation of the user
- Awareness and interaction design
- The dynamics of the biocybernetic loop
- Ethical implications, e.g. autonomy, privacy
How can we describe BCIs?
A system that translates measures of brain activity into commands or messages for an interactive application
There are two types of EEG-based BCI-Paradigm. Name this two and give a short description of each. Also show the communication flow between the user and the system.
What is the P300 in terms of EEG?
What are advantages of P300 BCI
- Relatively high accuracy
- Attending to targets is more explicit than imagining limb movement
- Large and distinctive component
- Relatively less training is required (cf., motor imagery)
- Relatively fast calibration time (i.e., 5-10 minutes)
- More likely to be relevant to non-clinical applications
- Multiple choice selection
- High information throughput
- Accessible to almost all healthy individuals and many
paralyzed patients
What are common signal processing methods for P300?
Preprocessing (e.g. Data acquisition from sensors or A/D conversion, typically 256 Hz)
Feature extraction and Classification e.g.:
* Calibration session to learn relevant feature vectors
* Classifier is trained and supervised using a classification algorithm
What is the Steady State Visual Evoked Potential (SSVEP)?
Oscillatory brain activity in the visual cortex that is synchronized to the frequency of a flickering stimulus.
Redesigning BCI interfaces
Describe a example how a BCI interface can be built.
Describe what cognitive load is and give an example how it can be measured.
Cognitive Load:
How much brain capacity is used
Measuring:
Estimating the cognitive load of a person by thermal imaging
(Forehead gets wormer with harder tasks)
