What kind of methods is needed to have this return a "someone moved to the left" message from analyzing the array?
The field of study this calls on is called pattern recognition and is a thing that is easy for you to do but hard for a computer. Therefore it is hard to program this to get what you would consider a good result.
What you need to do is to find the X-Y values for the "hot spot". If you have a liner array representing your physical two dimensional array you need to know how it is made up in order to come up with a way of converting the linear array value into an X-Y pair. This is the inverse of what you have to do when making an LED matrix from an addressable strip.
So suppose your array has the first 8 elements along the bottom row then the X coordinate is simply the remainder of the sensor number divided by 8 ( this is called the mod and the symbol for this is % ) and the Y coordinate is the integer result of dividing the sensor number divided by 8.
So find the hot spot coordinate pair and store it. Then scan again and find the new coordinate pair. Then you subtract one pair from the other to find the delta ( or difference ) between the two. If their has been sufficient change in say the X direction you can then output a message saying "Moved to the Left" or "Moved up".