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Intro to Object Recognition + Practice Questions
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A summary of lecture notes on object recognition, along with practice questions to help students better understand and test their knowledge on the concept. The note includes theories such as RBC, template, and functional.

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  • January 7, 2025
  • 9
  • 2024/2025
  • Class notes
  • Michael souza
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‭Lecture 05 - Object Recognition‬
🧠
‭ ‬‭The challenge of object recognition:‬‭linking current‬‭experience w/ past experience‬‭(memory)‬

‭Theories‬
🧠
‭ ‬‭template theory‬‭:‬‭recognizing objects as a whole rather‬‭than breaking it down into the parts that‬
‭make it up‬
‭○‬ ‭template‬‭: a memorized notion of something you’ve seen‬‭before‬
‭○‬ ‭when you see an object you align it to the template‬
‭○‬ ‭consistency‬‭is key for this theory‬
‭○‬ ‭requires you to have‬‭a template for every single thing‬‭you’ve seen in life‬‭, in every possible‬
‭orientation/angle you’ve seen it in‬
‭■‬ ‭that’s a lot of fucking brain space‬
‭■‬ ‭as we learn, new templates are created‬
‭○‬ ‭barcode anecdote‬
‭■‬ ‭a particular barcode is associated w/ a particular item in the entire store, likewise a‬
‭particular item in a particular orientation matches up with one of the million templates‬
‭in your mind‬
‭○‬ ‭the problem‬‭w/ this theory is that it‬‭assumes the‬‭brain is 10x larger‬‭than it actually is,‬‭cause‬
‭🧠‬‭CAPTCHA‬‭explained through‬‭template theory‬
‭○‬ ‭bots have difficulty computing the CAPTCHA tasks because they don’t align with any‬
‭templates the technology has‬
‭○‬ ‭gatekeepers bots from buying T-Swift tickets (except they’re becoming more advanced and‬
‭learning from humans completing the CAPTCHAs to bypass it‬
‭🧠‬‭feature analysis theories:‬‭recognizing an object by‬‭breaking it down into the parts‬‭that make it up‬
‭○‬ ‭an object is made up of a particular arrangement of features [lines, shapes, etc.]‬


‭➔‬ ‭The “T” is comprised of particular features‬‭that‬
‭are stored in our minds as mental representations,‬
‭when we notice those features together we realize‬
‭we’re looking at a “T”‬




‭🧠‬‭recognition by components (RBC):‬‭recognizing an object‬‭by its 3D components (referred to as‬
‭geons‬‭)‬
‭○‬ ‭think of it as the‬‭“lego theory”‬‭,‬‭geons = building‬‭blocks that can be combined to make sets‬
‭○‬ ‭states we have various geons in our minds that‬‭differ‬‭in terms of shape‬‭[contour, number of‬
‭connection points, symmetry, size, etc.]‬
‭○‬ ‭differs from feature analysis theory‬‭as it looks at‬‭a 3D shape rather than the features that would‬
‭make up a shape [i.e. lines]‬

, ‭○‬ ‭differs from template theory‬‭because you don’t need to have a geon in diff angles to recognize‬
‭the objects‬
‭■‬ ‭Biederman (theory developer) states, however, that you would need to see all the geons‬
‭of the object in order to recognize it‬
‭○‬ ‭a‬‭limitation‬‭to the theory is that it accounts for‬‭shape and orientation of the geons, but‬
‭doesn’t necessarily account for other physical properties that can differentiate objects from‬
‭each other [texture, colour, etc.]‬
‭🧠‬‭all theories have different viewpoints on whether or not the perspective in which the object is viewed‬
‭matters‬
‭○‬ ‭view-dependent:‬‭orientation‬‭matters‬‭in order to recognize‬‭an object‬
‭■‬ ‭i.e.‬‭template theory‬
‭○‬ ‭view-invariant:‬‭orientation‬‭does not‬‭matter‬‭in order‬‭to recognize an object‬
‭■‬ ‭i.e.‬‭RBC theory‬
‭🧠‬‭repetition suppression (RS):‬‭brain activity decreases‬‭when your brain gets used to looking at a‬
‭stimuli‬
‭○‬ ‭repetition‬‭:‬‭repeated exposure‬
‭○‬ ‭suppression‬‭:‬‭reduction in brain activity‬
‭○‬ ‭this phenomenon was discovered shortly after the development of fMRI‬
‭○‬ ‭to observe this phenomenon, you would use the subtraction method‬
‭■‬ ‭[neural activity for 1st presentation] - [neural activity for 2nd presentation]‬
‭●‬ ‭present a stimulus for the first time, note the brain areas that activate [i.e.‬
‭attention, visual perception, etc.]‬
‭●‬ ‭take the stimulus away for a bit‬
‭●‬ ‭present the stimulus again and take note on the activated brain areas‬
‭○‬ ‭you’ll notice that there would be less areas active since your brain is‬
‭getting used to the stimulus and has a better mental picture of it‬
‭○‬ ‭this reduction in brain activity‬‭doesn’t hinder recognition‬‭ability‬‭, rather is more about the‬
‭brain being‬‭more efficient‬‭when it recognizes objects‬
‭○‬ ‭hypothesis‬‭: each time you see a stimulus the brain‬‭fine tunes the features that make up the‬
‭object, filters out unnecessary features [i.e. the colour of an umbrella not an important‬
‭defining feature of umbrella]‬
‭○‬ ‭this theory can work for any visual stimulus [i.e. faces]‬
‭■‬ ‭the‬‭brain recalibrates when there’s a dramatic change‬‭[Kaaviya w/ straight blue hair]‬
‭🧠‬‭the fusiform area located in the temporal lobe is known for object recognition‬
‭🧠‬‭using RS to test out if perspective of an object’s orientation matters‬
‭○‬ ‭fusiform area in the left hemisphere = view-invariant‬
‭○‬ ‭fusiform area in the right hemisphere = view-dependent‬
‭○‬ ‭ergo, the brain is‬‭both view-invariant and view-dependent‬‭,‬‭depending on the side of brain‬
‭you’re looking at‬

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