Depending on what we are focusing on, our brains are sometimes completely oblivious to changes going on right in front of us that we would think would be quite obvious. This phenomenon is called change blindness, and I’m sure we have all experienced it in one way or another. Whether it be failing to notice a friend’s new haircut, something that could potentially be much more serious, such as missing a stop sign while driving down a road for the first time, or maybe someone has tried to trick you with this popular youtube video (http://youtu.be/Ahg6qcgoay4).
Or maybe you have witnessed change blindness second hand by watching one of the countless displays of the phenomenon caught on tape. Magicians like Darren Brown have provided us with perfect examples of change blindness, showing people fail to notice very dramatic changes.
It seems odd that we could fail to process such obvious changes going on right in front of our eyes. In some settings, change blindness has the potential to be very dangerous, especially with the developments of cell phones, mp3 players, and other mobile devices providing even more distractions than ever before. However, for the most part, it does not effect us any huge way. We are still able to function just fine in everyday life. The question I can’t help but ask myself is, “How can we possibly miss these obvious events? What is happening in our brains?”
Visual Attention and Short-Term Memory
So far, all experiments on change blindness share the proposal that attention is necessary to actually see change. Experiments on change blindness have found that we can only see 3-4 items change at a time, while there is often many more items changing in front of us. It is known that a limit in our perception is involved in change blindness, but the nature of this limit is still unknown. Change perception involves several steps: moving information to a memory store, consolidating it to a form usable by following processes, holding on to it for a short period of time, comparing it to the current stimulus clearing the memory store, and shifting to the next item. A limit of any of these steps would limit the entire process.
A couple of issues on this topic have emerged. The first is whether or not the limiting factor actually applies to the construction of the coherent representation, or to its maintenance after it has been formed. Another issue that has emerged is the nature of the elements that are held in visual short-term memory (vSTM). There is evidence suggesting that these are proto-objectes that have a substantial amount of local binding of features. If this is true, the function of attention and vSTM would be to produce a representation with extended spatial and temporal coherence.
Considering that we have a coherent representation of a few items at a time, we know that our subjective impression that we see everything that happens cannot be true. It has been proposed that scene perception is handled by a virtual impression within our brain, which accounts for the impression that we see all changes that occur in front of us. Here, coherent representation of objects are created on a ‘just in time’ basis. This means that they are formed when they are needed for a task and then they are dissolved.
No results so far have clearly shown storage of information beyond relatively scarce information used for guidance. When an item changes, information about the prior state of the item seem s to be stored in a longer-term memory which is not used for our perception of change. More generally, scenes might be stored in long-term memories of varying kinds, but the density of the information remembered could be quite low.
Research on change blindness has found that attention is necessary for the conscious experience of change. Without attention, we are blind to even large changes at a conscious level. Beyond this, the current knowledge base on the subject is quite poor. However, this topic is currently being researched in varying ways, and progress is being made.
- Damn you, change blindness! (turtlesplusrhinos.wordpress.com)
- You have to try this – Change Blindness (ediblepsychology.com)
- Another Cool Change Blindness Video: The Color Changing Card Trick (capitalogix.typepad.com)
- Awareness Test Video – Your Attention Span Is Smaller Than You Think (capitalogix.typepad.com)
- Blind man shoots for change of perception ()
- Does consciousness pose a particularly ‘hard’ problem? (consciousnessthoughts.wordpress.com)
- The Invisible Gorilla (scriptsuper.wordpress.com)
- Brought to you by the letter ‘C’… (myownprivateuniverse.wordpress.com)