| Course | PS200 Introduction to Cognitive Psychology |
|---|---|
| Unit | Unit 3 |
| Paper type | Working memory exercise |
| Length | About 540 words, 4 pages double-spaced |
| Format | APA 7 student paper |
| School | Purdue University Global |
| Program | BS in Psychology |
| Updated | October 2026 |
Free sample paper for PS200 Unit 3
Holding an Address While Typing a Name: A PS200 Unit 3 Working Memory Exercise
[Student Name]
Purdue University Global
PS200: Introduction to Cognitive Psychology
Unit 3 Working Memory Exercise
[Instructor Name]
[Date]
The call-taker and the practice trials are composite; the models and studies cited are real.
The Demonstration
I ran a simple demonstration on myself, with a coworker reading the items during a quiet hour at the end of a shift. In the first condition, the coworker read sequences of digits at one per second, and I repeated them back. I started at four digits and added one each time until I failed twice at the same length. My span was seven digits.
In the second condition, the coworker read a seven-digit house number and street, as a caller would, and then immediately spelled a caller's last name while I typed it into a practice form. Only after typing did I repeat the address. I tried this with eight different addresses. I recalled the full address correctly on three trials; on the others I lost or swapped one or two digits, and my reliable span fell to about five.
Typing a spelled name while holding an address cost me two digits of capacity.
Baddeley's Model
Baddeley and Hitch (1974) proposed that working memory is not a single store but a system with parts. The phonological loop holds sound-based information, such as spoken digits, by rehearsing it silently. The visuospatial sketchpad holds images and locations. The central executive directs attention among tasks and draws on both. Baddeley (2000) later added the episodic buffer, which binds information from different sources and from long-term memory into single episodes.
The model explains my results. In the first condition, the phonological loop rehearsed the digits without competition. In the second, the spelled name also arrived as speech and entered the same loop, interfering with rehearsal of the address. At the same time, the central executive was busy managing the typing. Both resources the address depended on were taxed.
How Many Items?
Miller (1956) famously suggested that people can hold about seven items, plus or minus two. My silent span fits that estimate. Cowan (2001) argued that when rehearsal and grouping are prevented, the true capacity is closer to four chunks. My typing condition, which interfered with rehearsal, produced a span between those estimates, which is consistent with Cowan's view that the number depends on how much rehearsal is possible.
What It Means for the Work
The exercise suggests that call-takers should not rely on working memory to carry an address across another task. Typing the address immediately, before asking for the caller's name, removes the competition. Grouping the digits into chunks, as people do with phone numbers, would also help. The results come from one person and eight trials, so they demonstrate the principle rather than measure it. A stronger test would compare several call-takers, alternate the order of the conditions so fatigue does not favor one of them, and use a nonverbal secondary task, such as tapping a pattern, to see whether a task that does not use the phonological loop costs less capacity than typing a spelled name. Baddeley's model predicts that it would.
References
Baddeley, A. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences, 4(11), 417-423. https://doi.org/10.1016/S1364-6613(00)01538-2
Baddeley, A. D., & Hitch, G. (1974). Working memory. In G. H. Bower (Ed.), The psychology of learning and motivation (Vol. 8, pp. 47-89). Academic Press. https://doi.org/10.1016/S0079-7421(08)60452-1
Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87-114. https://doi.org/10.1017/S0140525X01003922
Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81-97. https://doi.org/10.1037/h0043158
The Purdue Global PS200 Unit 3 instructions
Unit 3 of PS200 commonly asks you to demonstrate the limits of working memory and explain them with a model. Describe your demonstration precisely: what was presented, how fast, how many trials and how you scored recall. A digit span task is common; adding a second condition with a competing task makes the result more interesting. Report the results as numbers. Explain them with a model, usually Baddeley's, and map each condition onto the components it would load. Relate your numbers to estimates of capacity in the literature. Acknowledge the limits of a demonstration with one person and few trials, and suggest a better test. Finish with what the result means for a real task, citing the model's original sources in APA style.
How this PS200 Unit 3 example is built
The exercise describes a silent digit-span condition run with a coworker at the end of a shift, rising from four digits until two failures, and a second condition in which a seven-digit address was followed by a spelled surname typed into a practice form. Results give a span of seven in silence and about five under load, under a highlighted line on the two digits lost. A model section explains the loop, sketchpad, executive and buffer from Baddeley and Hitch and Baddeley's 2000 update, then maps each condition onto them. Capacity is discussed through Miller and Cowan. The close recommends typing the address first, chunking digits, and a stronger test with a tapping task.
Where the points sit in the PS200 Unit 3 rubric
Exercises in this unit earn credit for a clear method, honest results and a model applied to them. Instructors look for enough detail that someone could repeat the demonstration. Results reported as numbers score better than impressions such as it was harder. Mapping each condition onto specific components of the model shows understanding rather than recall of a diagram. Comparing the results with published capacity estimates, and explaining any difference, is valued. Acknowledging that one person and a handful of trials can only illustrate a principle earns credit for scientific caution. A practical application at the end connects the lab-style task to real life. Original sources for the model, cited in APA style, are expected.
PS200 Unit 3 help: mistakes that cost points
Many exercises describe the model in detail and give the demonstration a single sentence, which reverses the unit's priorities. Another common slip reports a span without saying how it was measured or when the test stopped. Students sometimes claim that their results prove the model, rather than illustrating or fitting it. The central executive is often described vaguely or confused with the whole system. Some papers cite seven plus or minus two as settled fact without noting newer estimates. Before submitting, check that a reader could repeat your demonstration from your description, that every result is a number, that each condition is linked to a model component, and that you have named at least one limitation.
Get a PS200 Unit 3 example written to your instructions
Send the exercise instructions and the rubric. A custom exercise runs a simple demonstration and explains the result with a working memory model. The first is free, back within 24-48h. The paper above is an original model document written by our desk, not a submitted student paper and not an official Purdue University Global document.
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PS200 Unit 3 questions, answered
What are the parts of Baddeley's model?
The central executive, the phonological loop, the visuospatial sketchpad and the episodic buffer.
How many items can working memory hold?
Estimates vary; many researchers now cite about four chunks rather than seven items.
Can I use a digit span task?
Yes, it is a common way to demonstrate the limit.
Where can I find a free PS200 Unit 3 sample paper?
The complete PS200 Unit 3 exercise is on this page, demonstrating working memory limits with a composite call-taker's digit span and a typing condition.
Why did recall drop while typing in the PS200 Unit 3 sample?
The spelled name and the address both used the phonological loop, and the central executive was busy managing the typing.