o They focus on how it is that we build internal representation of objects

O they focus on how it is that we build internal

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o They focus on how it is that we build internal representation of objects during the process of recognition. Pattern Recognition: The ability to recognize an event as an instance of a particular category of event. Percept: Meaningful interpretation of sensory information. Recognizing a configuration involves contact between the emerging percept and memory. Memory Trace: The trace that an experience leaves in the brain. To recognize a letter “a,” your emerging perception of “a” must make contact with the memory trace of “a.” o This process is called the Hoffding function : When an experience makes contact with a memory trace, resulting in recognition. Template Matching Template: A model against which a stimulus is compared to determine whether it belongs to a particular category. Prototype: A model that possesses all the typical characteristics of its class. Template matching theory: Comparing a stimulus with templates; when they match, the stimulus is recognized as belonging to that category. o Problem: How to specify a template can match not only patterns that are identical to it, but also patterns that are similar enough to it. Multiple-trace memory model - Hintzman: Traces of each individual experience are recorded in memory. No matter how often a particular kind of event is experienced, a memory trace of the event is recorded each time. o This approach distinguishes between primary and secondary memory: Primary: what we experience at any point in time. Secondary: all the memory traces created out of all the experiences we’ve had. Secondary memory can be activated by a probe from primary memory. o When a probe goes out from primary to secondary memory, then memory traces are activated to the extent that they are similar to the probe. o The activated memory traces return an echo to primary memory. o The echo is made up of contributions from all the activated memory traces. Experiment with prototypical patterns showed that: o Prototypical patterns were quite well classified, even though they had never been seen before. o Sometimes participants falsely recognized the prototype as a pattern they had seen before, even though they had previously only seen distortions of the prototype. Hintzman’s explanations for these results:
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o Memory traces of the set of distorted patterns produce an echo which contains what the different distortions have in common and that’s how the prototype is recognized. Once an echo has been experienced in primary memory, it can leave a memory trace of itself in secondary memory. Feature Detection Feature Detection Theory – Selfridge: o Detecting patterns on the basis of their individual features. Pandemonium : A model of pattern recognition consisting of three levels: data, cognitive demons, and decision demons! o Data level: features such as size, color, shape… o Cognitive demons: Feature detectors that decide whether the stimulus matches its pattern.
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  • Spring '09
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