Free MCAT-style practice, 6B
MCAT Memory Encoding, Retrieval and Forgetting Practice Questions
Ten free MCAT-style practice questions on memory encoding, storage systems, retrieval, interference, false memories and the neural basis of memory, with full explanations.
Quick concept primer
Memory has three stages: encoding, storage and retrieval. Encoding is strongest when it is semantic and elaborative, which is the core of Craik and Lockhart's levels of processing idea. In the Atkinson and Shiffrin model, information passes from brief sensory memory to a limited short-term store and then to long-term memory. Baddeley and Hitch recast short-term memory as working memory, with a phonological loop, a visuospatial sketchpad, a central executive and later an episodic buffer. Long-term memory divides into explicit memory (episodic and semantic) and implicit memory (procedural skills, priming and conditioning).
Retrieval works best when cues at test match those at encoding, as in context-dependent and state-dependent memory. Forgetting comes from decay, retrieval failure and interference, and Ebbinghaus showed that relearning reveals memory that recall misses. Memory is reconstructive, so later information can alter it (Loftus). Biologically, the hippocampus consolidates new explicit memories, and long-term potentiation, which depends on NMDA receptors, strengthens synapses.
Traps: proactive interference is old learning disrupting new learning, and retroactive is new disrupting old. Anterograde amnesia blocks new memories after an injury, and a person with hippocampal damage can still learn new motor skills.
10 practice questions
Question 1
In a study, participants answered one question about each of 60 words without knowing a memory test would follow. For some words they judged whether it was printed in capital letters, for some whether it rhymed with a target, and for some whether it fit into a sentence. A surprise free-recall test gave the results below.
| Judgment made at study | Percent recalled |
|---|---|
| Capital letters? | 14 |
| Rhymes with target? | 27 |
| Fits the sentence? | 58 |
Which concept best explains this pattern?
- Depth of processing: semantic encoding produces stronger memories
- The serial position effect
- State-dependent retrieval
- Proactive interference from earlier words
Show answer and explanation
Answer: A. Depth of processing: semantic encoding produces stronger memories
The three judgments require structural, phonemic and semantic processing, and recall rises with depth, as Craik and Lockhart's levels of processing framework predicts. Word position was not manipulated, so serial position does not apply. Internal state was the same throughout, and nothing about interference would favor the sentence judgments specifically.
Question 2
Participants heard 15-word lists. In condition 1 they recalled each list immediately. In condition 2 they counted backward by threes for 30 seconds before recalling. Compared with condition 1, which change is most likely in condition 2?
- Recall of the first few words drops, while recall of the last few words is unchanged
- Recall of the last few words drops, while recall of the first few words is largely unchanged
- Recall of all positions rises because the delay allows consolidation
- Recall of middle words rises above recall of the first words
Show answer and explanation
Answer: B. Recall of the last few words drops, while recall of the first few words is largely unchanged
The recency effect reflects words still held in short-term memory, and a filled delay displaces them, so recency disappears. The primacy effect reflects early words that received extra rehearsal and reached long-term memory, so it survives the delay. Choice A reverses the two effects, and a 30 second distractor task does not improve recall.
Question 3
A volunteer needed 24 trials to learn a list of nonsense syllables perfectly. Two weeks later she could not recall any syllables, but she relearned the list in 9 trials. What is her savings score?
- 37.5 percent
- 50.0 percent
- 15.0 percent
- 62.5 percent
Show answer and explanation
Answer: D. 62.5 percent
Savings equals (original trials minus relearning trials) divided by original trials, which is (24 - 9) / 24 = 0.625, or 62.5 percent. Choice A is 9 / 24, the relearning fraction rather than the savings. The result shows that memory remained even though free recall was zero.
Question 4
A student studied Spanish in high school and began Italian in college. When she now tries to recall Spanish words, similar Italian words keep coming to mind instead. Which process best describes this?
- Proactive interference
- Retroactive interference
- Decay of the memory trace
- Source amnesia
Show answer and explanation
Answer: B. Retroactive interference
Newer learning (Italian) is disrupting retrieval of older learning (Spanish), which is retroactive interference. Proactive interference would be Spanish intruding while she tries to learn or recall Italian. Decay does not explain why specific competing words intrude, and source amnesia is forgetting where a memory came from.
Question 5
Participants watched a slideshow of a man taking a wallet from a store counter. He wore no hat. Afterward, half read a summary that mentioned the man's red cap, and half read an accurate summary. A week later, many in the first group reported clearly seeing a red cap, while few in the second group did. This result best demonstrates
- the misinformation effect, showing that memory is reconstructed at retrieval
- a flashbulb memory created by an emotional event
- the encoding specificity principle
- retrograde amnesia for the original slideshow
Show answer and explanation
Answer: A. the misinformation effect, showing that memory is reconstructed at retrieval
Misleading information supplied after the event was blended into the memory, so people recalled a detail that never appeared. This is the misinformation effect studied by Loftus, and it shows that memory is reconstructive. A flashbulb memory is a vivid recollection of a shocking personal event, and nothing suggests lost memories or a mismatch between study and test context.
Question 6
After surgery removed most of both medial temporal lobes, a patient could not remember people he met after the operation. Over several days of practice, however, he became steadily faster at tracing a star seen only in a mirror, while saying each time that he had never done the task. Which conclusion is best supported?
- Working memory and long-term memory depend on the same structures.
- Medial temporal structures are needed to form new explicit memories but not to acquire procedural skills.
- The patient has retrograde amnesia limited to procedural memory.
- Procedural memory requires conscious recollection of earlier practice.
Show answer and explanation
Answer: B. Medial temporal structures are needed to form new explicit memories but not to acquire procedural skills.
The patient cannot form new declarative memories (anterograde amnesia) yet improves at a motor skill, so procedural learning relies on other systems such as the basal ganglia and cerebellum. Choice D is contradicted because he improved without remembering practice. His loss concerns new explicit memories, not old procedural ones.
Question 7
In hippocampal slices, a brief burst of high-frequency stimulation normally produces a lasting increase in the size of postsynaptic responses. If a drug that blocks NMDA receptors is applied before the burst, what is the most likely result?
- The lasting increase still occurs, because AMPA receptors carry the initial current.
- The response becomes permanently larger than normal.
- The lasting increase fails to develop, because Ca2+ entry through NMDA receptors is prevented.
- Long-term depression is produced in place of potentiation in every case.
Show answer and explanation
Answer: C. The lasting increase fails to develop, because Ca2+ entry through NMDA receptors is prevented.
Inducing long-term potentiation requires glutamate binding plus depolarization that expels the Mg2+ block from NMDA receptors, letting Ca2+ enter and trigger AMPA receptor insertion. Blocking NMDA receptors prevents that Ca2+ signal, so LTP does not form. AMPA receptors carry ordinary transmission but cannot induce LTP alone, and the blocker does not reliably convert the result into depression.
Question 8
Participants held a list of six spoken digits in mind while doing a second task. Repeating the word "the" aloud over and over impaired digit recall sharply, but tapping a spatial pattern on a keypad did not. Which component of Baddeley's working memory model does the digit task most rely on?
- The visuospatial sketchpad
- The episodic buffer
- Iconic memory
- The phonological loop
Show answer and explanation
Answer: D. The phonological loop
Saying a word repeatedly (articulatory suppression) occupies the phonological loop, which holds verbal and acoustic information through subvocal rehearsal, so it disrupts digit recall. A spatial tapping task loads the visuospatial sketchpad and left recall intact. Iconic memory is a brief visual sensory store, not a working memory component.
Question 9
All of the following are forms of explicit (declarative) memory EXCEPT
- recalling the details of your first day at a new job
- knowing that the Pacific is the largest ocean
- remembering where you parked this morning
- touch-typing a sentence without looking at the keyboard
Show answer and explanation
Answer: D. touch-typing a sentence without looking at the keyboard
Touch-typing is a procedural skill expressed through performance without conscious recollection, so it is implicit memory. Remembering a first day at work and where you parked are episodic memories, and knowing which ocean is largest is a semantic fact. Episodic and semantic memories are both explicit.
Question 10
Members of a diving club learned a word list either on the beach or underwater and were then tested in the same or the other setting. Mean words recalled are shown below.
| Learned | Tested on beach | Tested underwater |
|---|---|---|
| On beach | 12.8 | 8.4 |
| Underwater | 8.9 | 11.6 |
Which conclusion is best supported by these data?
- Underwater learning is generally superior to learning on land.
- Recall depends mainly on testing location, regardless of where learning occurred.
- Recall is best when the retrieval context matches the encoding context.
- The underwater setting impairs encoding but not retrieval.
Show answer and explanation
Answer: C. Recall is best when the retrieval context matches the encoding context.
Matched conditions (12.8 and 11.6) beat mismatched ones (8.4 and 8.9) for both learning settings, which is context-dependent memory and fits Tulving's encoding specificity principle. Beach learning actually gave the highest score, ruling out A. Each testing location helped one group and hurt the other, so location alone does not explain the pattern.