Questions: Working Memory Development and Capacity Constraints

Question 1

A 7-year-old and an adult are both asked to remember the phone number 555-867-5309 after hearing it once. The adult is much more likely to succeed. What best explains this advantage?

• A. Adults have larger raw storage capacity because their prefrontal cortex is fully developed
• B. Adults can chunk '555', '867', and '5309' as familiar digit groups, fitting 10 digits into 3 meaningful units
• C. The adult has likely heard this specific number before and retrieved it from long-term memory
• D. Adults have faster processing speed, allowing more rehearsal repetitions before the memory fades

Answer: (B)

This illustrates chunking: rather than holding 10 separate digits, the adult groups them into 3 familiar units — area code, exchange, number — fitting comfortably within working memory's limited capacity. The 7-year-old, lacking experience with telephone number formats, must hold each digit separately. The adult's advantage comes from prior knowledge enabling compression, not a larger storage tank. Processing speed (option D) plays a real role in development but doesn't capture the key mechanism here.

Question 2

A first-grade teacher notices that some students understand individual words but still can't follow a complex sentence like 'The dog that the cat chased ran away.' What does working memory development research suggest about why this happens?

• A. The children have a vocabulary gap and don't know what 'chased' means in this syntactic context
• B. The children cannot hold the beginning of the sentence in working memory while processing the embedded clause, so the subject slips away before the sentence resolves
• C. Complex syntax is a separate cognitive skill from working memory and develops on a different timeline
• D. The children are processing the sentence correctly but confusing which animal was doing the chasing

Answer: (B)

Parsing 'the dog that the cat chased ran away' requires holding 'the dog' as the subject in working memory while processing the embedded relative clause 'that the cat chased,' then returning to complete the main clause. Children with limited working memory capacity may lose the thread — the subject slips out before the sentence resolves. This is why working memory is a key substrate for reading comprehension: syntactic processing requires actively maintaining sentence elements across time, not just knowing word meanings.

Question 3

The developmental increase in working memory capacity from early childhood to adulthood is driven largely by brain maturation — specifically, the protracted development of the prefrontal cortex.

• T. True
• F. False

Answer: False

While prefrontal cortex maturation is a real and important contributor to working memory development, it is not the sole driver. The development of chunking strategies — which depend on accumulating semantic knowledge — plays an equally important role by increasing the information density of each working memory slot. A child learning to read, for example, gradually stops holding individual letters in memory and starts grouping them into words, then phrases. This strategy development depends on accumulated knowledge, not just neural maturation.

Question 4

An expert chess player can recall the positions of most pieces after a brief glance at a mid-game board, while a novice can remember mainly a few. This demonstrates that domain experts have larger raw working memory capacity than novices.

• T. True
• F. False

Answer: False

Classic research by Chase and Simon showed that chess experts' advantage disappears when pieces are placed in random (non-game-realistic) positions. This proves the advantage is not from larger raw capacity but from chunking: experts recognize meaningful patterns ('fianchettoed bishop,' 'isolated pawn') and encode entire configurations as single chunks. The expert holds 3–4 pattern chunks, each encoding many pieces; the novice holds 3–4 individual pieces. Domain expertise expands functional capacity within the domain by enabling more powerful chunking, not by increasing the raw number of slots.

Question 5

Why do domain experts appear to have larger working memory capacity within their domain, even though experimental evidence shows their raw working memory capacity is no different from novices?

Model answer: Domain experts have accumulated rich semantic knowledge that allows them to chunk multiple items into single meaningful units. A chess expert sees not 'knight on e5, pawn on d4, bishop on c3' but a single recognizable tactical pattern — one chunk encoding many pieces. This compression means each working memory slot carries more information. The slots are the same size; what goes in them is denser. Without domain knowledge, there's nothing to chunk, so the raw capacity limits become apparent.

This is the key insight separating understanding from memorization: working memory development is not just about a tank getting bigger — it's about learning to pack more into the same tank. Chunking is the mechanism, and domain knowledge provides the chunks. This explains why reading widely and building semantic knowledge indirectly expands effective working memory capacity across domains.