Week 9 Flashcards
What is backpropogation?
When a machine learns by guessing, finding how far they are, and using that info to guess again more accurately until answer is reached
Wha is unsupervised data?
Finding patterns in data WITHOUT needing labels
What is the k-means clustering algorithm?
- Points in a scatterplot are randomly assigned to k groups
- Centroid (avg distance between all points in group) is calculated
- Each point distance compared against each centroid
- Info on distance tells machines which points are actually closer to each other
- Points are regrouped
Is k-means clustering considered unsupervised data?
Yes
What is a decision tree?
The calculation of how the combination of different possible features may influence an outcome (ex: result of temp, weather, and humidity decides if we play tennis or not)
Do all features predict the result of the outcome to similar effectiveness?
No
What is Electroencephalography (EEG)?
Machine that records brain activity using electrodes to record voltage fluctuations on the scalp
What is the event related potential (ERP)?
A way to more clearly see brain activity patterns
How do you calculate the event related potential (ERP)?
Measure the EEG signals from time t to an end time many times over and determine the average
What are ERP components?
EEGs combine brain activity from multiple areas in the brain - the individual brain data pieces are ERP components
What is the P300?
A positive ely deflecting ERP that shows up in response to certain attention-grabbing stimuli 300ms after stimulus is presented
What is the training phase of this test?
Shows many examples of your letter flashing and not flashing to record how your brain responds to both situations
Is everyone’s P300 patterns the same?
No
What happens after training phase?
The P3 speller creates scatterplot of data and creates line between yes responses and no responses
What happens during testing phase?
P3 speller can identify which letters are being thought of (considered in “yes” category) and which are not (considered “no”)
What is a BCI?
A direct communication pathway between the brain and an external divide (includes EEGs).
