Short term memory tasks are hard bc of the short duration and the small capacity of short term memory. Two definitions of memory: the process involved in retaining, and using information about stimuli, images, events, ideas, and skills after the original info is no longer present. It"s active anytime some past experience has an effect on the way we think/behave now or in the future. So memory is about the past affecting the present and the future. These types of memory are the structural features of the model: the underlying principles that govern the solution to the model. Encoding is storing the number in long term memory. Retrieval is remembering info that is stored in long term memory. The components of memory do not act in isolation. This is the retention, for brief periods of time, of the effects of sensory stimulation (for ex: watching a movie).