Showing posts from November, 2007

Confirmation bias as a tool of perception

I've been trying to figure out where to go next with my study of perception. One concept I'm exploring is the idea that our expectations enhance our ability to recognize patterns. I recently found a brilliant illustration of this from researcher Matt Davis , who studies how humans process language. Try out the following audio samples. Listen to the first one several times. It's a "vocoded" version of the plain English recording that follows. Can you tell what's being said? Vocoded version. Click here to open this WAV file Give up? Now listen to the plain English version once and then listen to the vocoded version again. Clear English version. Click here to open this WAV file Davis refers to this a-ha effect as "pop-out": Perhaps the clearest case of pop-out occurs if you listen to a vocoded sentence before and immediately after you hear the same sentence in vocoded form. It is likely that the vocoded sentence will sound a lot clearer wh

What bar code scanners can tell us about perception

It may not be obvious, but a basic bar code scanner does something that machine vision researchers would love to see their own systems do: find objects amidst noisy backgrounds of visual information. What is an "object" to a bar code scanner? To answer that, let's start by explaining what a bar code is. What is a bar code? You've probably seen bar codes everywhere. Typically, they are represented as a series of vertical bars with a number or code underneath. There are many standards for bar codes, but we'll limit ourselves to one narrow class, typified by the following example: This sort of bar code has a start code and an end code. These typically feature a very wide bar. One of its main purposes is to serve as a standard for bar widths. This is sometimes 4x the unit width for a bar. The remaining bars and gaps between them will be some multiple of that unit width (e.g., 1x, 2x, or 3x). Each sequence of bars and gaps relates to a unique number (or letter or other