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Cognitive Neuroscience (Fach) / Perceptual Decision Making (Lektion)
Perceptual Decision Making - not finished
Diese Lektion wurde von Habana erstellt.
Diese Lektion ist leider nicht zum lernen freigegeben.
- Explain Signal Detection Theory. Signal detection theory states that every perceptual signal contains 'real signal' and noise. There are two factors: Presence of signal (either yes or no) and Detection of signal (either yes or no). Presence yes/Detection yes = Hit Presence yes/Detection no = Miss Presence no/Detection yes = False Alarm Presence no/Detection no = correct rejection The model, however, only explains decision outcome and not how decisions are formed over time.
- What is meant by sequential analysis? What are its subcategories? Sequential analysis is a model that explains decision making over time. Frame work: Between timepoint e0 and e1, a decision can be formed. Each timepoint e reflects a time where new information is gained. This process is repeated until we don't need more information to form the decision. In the symmetric random walk the decision has to be made between event is present and event is not present (e.g. light is red or light is not red). The evidence for one of the two options is accumulated until it reaches a threshhold (either the one for event is present or for event is not present). The threshhold is defined by context variables, such as the value of the decision or the reward/punishment expected for either one of the decisions. The race model is similar to the symmetric random walk. Here decisions between one event or another event (e.g. is the light red or green) are made. Evidence for both events is accumulated independently. The decision is made for the event for which the threshhold is reached first.
- Explain a typical decision task for macaque monkeys and the role of MT and LIP neurons. A typical decision task is the random dot paradigm, in which monkeys look at a screen with a number of dots moving randomly around the screen. Some of the dots (the number can be varied to change task difficulty) move in one coherent direction. The monkey has to detect the direction and make a saccade to the correct direction. The firing rates of single neurons in MT (middle temporal area - motion perception) and LIP (lateral intraparietal area- eye movement planning) were recorded. MT's firing rate represents stimulus strength at timepoint x (the stronger the evidence/the more dots are moving in the same direction, the higher MT's firing rate). LIP, however, accumulates the evidence coming from MT until its firing rate reaches a threshhold upon which a saccade is made. Thus, when sensory evidence is weak it takes longer to reach the threshold and execute the movement.