Perception is not a key aspect of cognitive processing in multimedia systems. Attention, memory, and emotion are the primary aspects.

Perception is the process of organizing and interpreting sensory information.

Sensory memory is not a type of memory involved in multimedia processing. Short-term memory, long-term memory, and working memory are the primary types.

Selective attention is the ability to focus on a specific stimulus while ignoring others.

Proximity is the tendency to perceive objects as belonging together based on their proximity.

Cognition is the process of mentally representing and manipulating information.

Sustained attention is the ability to maintain focus on a task over an extended period.

Similarity is the tendency to perceive objects as belonging together based on their similarity.

Continuity is the tendency to perceive objects as belonging together based on their connectedness.

Closure is the tendency to perceive an incomplete object as complete.

Complexity is not a key principle of interaction design in multimedia systems. Consistency, feedback, and affordance are the primary principles.

Consistency is the principle of ensuring that elements in a user interface are consistent in their appearance and behavior.

Feedback is the principle of providing users with information about the results of their actions.

Affordance is the principle of designing objects so that their intended use is clear and obvious.

Simplicity is the principle of designing user interfaces with a minimal number of elements and clear visual hierarchy.