Richard Atkinson and Richard Shiffrin proposed a three-phase model to explain the memory forming process. This included in order:

1. Recording to-be remembered information as sensory memory. This is when external events cause a sensory input (stimulus). It's this fleeting occurrence that will be processed as a sensory memory. 

2. Information is then processed into short-term memory. At this time, the information is encoded into our brains through rehearsal. 

3. For future retrieval, information then moves into long-term memory.

This model has been updated since Atkinson and Shiffrin's time by other psychologists to now include working memory and automatic processing. Working memory is the middle ground for processing. It may be thought  to occur at the same time as short-term memory processing. At this time, information is merely actively (working) processed while short-term memory processes it to be sent to long-term memory. Automatic processing is the direct pathway by which external events are automatically processed into long-term memory.

Baddeley and colleagues disagreed with Shiffrin and Atkinson's idea about short-term memory. Shiffrin and Atkinson viewed short-term memory to be a brief "holding" shelf for information as it is passed along to long-term memory. Baddeley and colleagues discovered this to be incorrect. Short-term memory isn't just a temporary passing stage to hold information, but it is an active desktop where information is actively processed. This middle stage is responsible for linking incoming information with previously stored information. 

This added to Shiffrin and Atkinson's model for memory processing by replacing/combining the short-term memory stage with working memory. Here information from sensory memory is stored and processed by maintenance and rehearsal. Eventually the information will be ready to be encoded into long-term memory.

Our minds operate on a two-track system; this is also known as dual-track memory. This system operates with us consciously processing information (effortful processing) while there is also information behind the scenes that is automatically processed into storage (automatic processing). 

Conscious processing occurs for declarative (explicit) memories. These are memories that we consciously aware of, such as facts and experiences we focus on. Automatic processing occurs for the experiences and occurrences we are not aware of. These memories are known as non-declarative, or implicit, memories. These memories skip our conscious encoding and go directly to storage.  

Sensory memory is the beginning to memory processing. Upon sensory stimuli (input), the information will be stored as a fleeting sensory memory, which will soon be encoded into short-term/working memory. From this middle stage, the information will be rehearsed and maintained until it is encoded into long-term memory/storage.  

Sensory memory is exactly what it sounds like - memory that pertains to stimuli observed by the senses. Sensory memory may be divided into echoic memory and iconic memory. Echoic memory relates to a fleeting sensory memory for auditory stimuli. Iconic memory relates to a fleeting sensory memory for visual stimuli. 

Sensory memory is memory that pertains to stimuli observed by the senses. Sensory memory may be divided into echoic memory and iconic memory. Echoic memory relates to a fleeting sensory memory for auditory stimuli, where the echo of a sound will be encoded into memory. Iconic memory relates to a fleeting sensory memory for visual stimuli, where an image will be encoded into memory. 

Sensory memory is the beginning to memory processing. Upon sensory stimuli (input), the information will be stored as a fleeting sensory memory, which will soon be encoded into short-term/working memory. From this middle stage, the information will be rehearsed and maintained until it is encoded into long-term memory/storage. Given that both iconic and echoic memory play similar roles for sensory memory, it would be incorrect to initially deduce that one plays a greater role in the different stages of memory processing than the other. 

Chunking, mnemonics, hierarchies, and distributed practice may seem familiar as studying techniques. These are in fact effortful processing strategies that will aid in remembering new information. Chunking is the strategy by which we organize information into familiar units; this is often automatically done. Mnemonics aid with memory via techniques that use vivid imagery or organizational devices. A well-known example of a mnemonic device is "Please Excuse My Dear Aunt Sally" for mathematical order of operations (PEMDAS). Hierarchies are a little like chunking, but the individual will remember a few broad concepts that will be divided into narrower and narrower concepts. This is a strategy that enables us to organize information. Distributed practice is merely spacing our encoding over a period of time. This revisit the familiar idea of it being more beneficial to space out study time over a few days or weeks as opposed to "cramming" the night before a test. 

Iconic sensory input would not be a strategy for effortful processing because it is part of memory processing. This is the stimulus that will register as a fleeting sensory iconic (visual) memory. This information does not necessarily have to be processed through effortful processing as a declarative memory. This information may be processed as non-declarative memory through automatic processing as it may have been information we were not consciously aware of. In this case, the information would be automatically processed into long-term memory, skipping short-term and working memory.

Retroactive interference is when newly learned information causes people to forget old information.

Thomas decides to finish his physics homework before starting his long night of biochemistry studying because he does not want any of the material from his physics assignment to interfere with the concepts he has to study for his biochemistry exam. In doing so, Thomas avoids retroactive interference, which occurs when learning new information makes it harder to recall something learned earlier. If Thomas had studied biochemistry before doing his physics assignment, then there would be an increased probability that the physics assignment might obscure his knowledge of the biochemistry concepts he had studied beforehand.

Effortful processing occurs when something necessitates our conscious effort and attention to commit something to memory. This most often occurs with complex ideas or tasks and things that do not automatically catch our attention or may not immediately interest us.

Contrary to popular belief, big "cramming sessions" are not effective ways to remember material. Rather, the spacing effect phenomena demonstrates that studying things in small chunks with measured periods of time in between fosters better memory encoding.