Information processing model: Sensory, working, and long term memory | MCAT | Khan Academy

Main Ideas & Concepts (Information-Processing Model of Memory)

The video explains how the brain stores and later retrieves information using the information-processing model, which compares the brain to a computer:

• Input from the environment
• Processing of that input
• Output in the form of decisions/actions

This model is conceptual, meaning it describes how memory works rather than mapping exactly where each process occurs in the brain.

Memory is organized into three main stages (plus supporting subcomponents):

1. Sensory memory
2. Working memory
3. Long-term memory

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Method / Flow of the Model (Step-by-Step)

1) Input Stage: Sensory Memory (Sensory Register)

What it is: A temporary store holding information arriving through the senses.

Key studied modalities:

• Iconic memory = what you see (visual information)
• Echoic memory = what you hear (auditory information)

Duration depends on modality:

• Visual (iconic): lasts less than ~0.5 seconds
• Auditory (echoic): lasts ~3–4 seconds

Example:

• If someone thinks you’re not listening during a conversation, echoic memory can still preserve what was last said.

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2) Processing Stage: Working Memory (Short-term Memory)

What it is: The information you are actively thinking about right now.

Capacity limit: “magic number 7”

• Holds about 7 ± 2 items (~5 to 9 pieces of information)
• Varies depending on:
  • how complex the information is
  • the person’s age

Why phone numbers became commonly 7 digits:

• It was thought to match typical working-memory capacity, reducing confusion.

Working Memory Subcomponents

• Visuo-spatial sketchpad

  • Processes visual and spatial information (e.g., pictures, maps)

• Phonological loop

  • Processes verbal information (words and numbers)
  • Example: repeating a phone number long enough to type it

Central Executive + Episodic Buffer

• Central executive

  • Coordinates between the visuo-spatial sketchpad and the phonological loop
  • Example: a map that includes both:
    • landmarks (visual/spatial)
    • street names (verbal)

• Episodic buffer

  • Acts as a connector to long-term memory
  • Receives an integrated representation created by the working-memory components

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3) Storage Stage: Long-Term Memory

What it is: The final storage stage in the information-processing model.

Analogy: Like pressing Save on a computer (with the caveat that human memory is not perfectly reliable).

Long-term memory is divided into two main categories:

1. Explicit (Declarative)
2. Implicit (Non-declarative)

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Explicit / Declarative Memory (Memories You Can Describe)

• Semantic memory

  • Facts and general knowledge you can state
  • Example: vocabulary tests, remembering state capitals
  • “Semantic” relates to words/meaning

• Episodic memory

  • Memories for specific events (e.g., “your last birthday party”)
  • Stores event sequences similarly to how a TV episode has an order of events

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Implicit / Non-declarative Memory (Memories You May Not Articulate)

• Procedural memory

  • Skills and procedures you perform without easily explaining how
  • Example: riding a bicycle

• Priming

  • Previous experience influences how you interpret current information
  • Example using the word “hair”:
    • If primed with a bunny picture earlier, you may interpret “hair” as “H-A-R-E” (rabbit)
    • If not primed (or if “hair” is more recently relevant), you interpret it as “H-A-I-R” (common word)

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Long-Term Capacity

While working memory feels limited moment to moment, long-term memory capacity is described as effectively unlimited (as far as is known).

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Speakers / Sources Featured

• Khan Academy (the content is from Khan Academy; no individual speaker name is provided in the subtitles).