Week 2-The phenomenon of Sensitization

In the last post, we discussed habituation and dishabituation, so let’s move to the next phenomenon related to learning- the phenomenon of sensitization. Habituation is when repeated exposure to a stimulus causes a weaker response to that stimulus, but the phenomenon of sensitization does the opposite; it enhances the response. Here, a high arousal stimulus cause for enhanced response to further stimuli. Let's go with an example.

Just imagine an encounter with a spider, where the spider was found on your feet. Most people will make a sudden jerk movement with their legs so as to get rid of that spider. Now the spider is not on your feet- relief, but you realize it’s out of sight. But if something like a thread or some fly comes into contact with your feet or somewhere on your body, what will be your reaction; it will probably be a stronger jerking response (unless you are not scared of the spider). This heightened response to the further, non-threatening stimuli is because of the sensitization stimuli (the spider on your feet), as it gets you in a high arousal state of fear; any further stimuli, even a thread of your blanket, can have a stronger response. We can even think of horror movies as an example of this. During those movies, some sudden sounds can get us into a state of fear, which can act as sensitization stimuli, and any further low-impact stimuli, such as some friends calling us or tapping on our shoulder, can have a much stronger response from our side. Similar to the process of dishabituation, there’s desensitization, where the impact of sensitization stimuli will go less, and the system will come to a state of reset (normal response to stimuli). Sensitization stimuli need not be repetitive, like habituation, but if the stimuli order is reversed, the impact can be reversed. This is called PPI (pre-pulse inhibition). We will discuss this more in an upcoming post.