In Shepard and Metzler's mental rotation studies, reaction time increased linearly with the angular difference between two shapes. Which theoretical interpretation does this most directly support?
APropositional theories, because symbolic processing takes longer for more complex angular descriptions
BDepictive (analog) theories, because the continuous time-angle relationship suggests a mental image being continuously rotated
CBoth theories equally, because any mental process that takes more steps takes more time
DNeither theory, because the linear effect could be entirely due to demand characteristics
The linear relationship between rotation angle and reaction time is the signature of analog representation. If imagery were purely propositional — a list of symbolic features — there would be no principled reason for time to scale continuously with angle; comparing feature lists doesn't take longer just because the original objects were rotated more. The continuous scaling implies that something is being mentally traversed through intermediate positions, like physically rotating an object. Pylyshyn's demand-characteristics counterargument (option D) remains a live theoretical worry but does not fully account for the neural evidence.
Question 2 Multiple Choice
A researcher concludes from the mental rotation RT-angle relationship that mental images are photographic copies of visual scenes, stored and replayed like digital images. What is the correct response to this claim?
AThe researcher is correct — the analog nature of imagery proves mental images are photographic
BThe result supports analog representation, but mental images are constructive, incomplete, and systematically distortable — not accurate photographic copies
CThe researcher is wrong because all imagery is purely propositional and the RT effect has a different explanation
DThe result is ambiguous and provides no information about the format of mental representation
Mental images are constructions, not recordings. They can be incomplete (people cannot visualize all parts of a complex scene simultaneously), flexible (you can mentally zoom, rotate, or transform images), and error-prone in ways photographs are not (people systematically misremember relative sizes, positions, and details). Kosslyn's depictive theory claims images are quasi-pictorial representations in a spatial medium — not that they are photographs. The 'mental photograph' misconception is common because 'seeing' a mental image feels like viewing a picture, but the underlying representation is far more dynamic and schema-driven.
Question 3 True / False
Neuroimaging studies have shown that early visual cortex (V1) is activated during mental imagery, suggesting that imagery partially engages the same neural machinery as visual perception.
TTrue
FFalse
Answer: True
This is well-established neuroimaging and TMS evidence. V1 normally receives bottom-up input from the retina, but during mental imagery it receives top-down activation from higher cortical areas. TMS studies showed that disrupting V1 impairs both perception and imagery. This supports the view that imagery is not a purely abstract symbolic process but involves running the perceptual system 'offline' — activating sensory areas without corresponding retinal input.
Question 4 True / False
The debate between depictive and propositional theories of mental imagery has been definitively settled in favor of the depictive view, based on the mental rotation findings and supporting neuroimaging evidence.
TTrue
FFalse
Answer: False
The debate is not settled. Pylyshyn's propositional critique — that subjects produce the expected RT-angle relationship because they have tacit knowledge about how rotation works — cannot be easily dismissed by behavioral evidence alone, since any RT pattern could in principle be mimicked by a propositional system with the right knowledge. The neural evidence is more compelling but still doesn't conclusively rule out propositional accounts. Contemporary consensus acknowledges that imagery has both analog spatial properties and symbolic/propositional aspects — neither pure depictive nor pure propositional theory fully captures all the evidence.
Question 5 Short Answer
Why does the linear relationship between rotation angle and reaction time in mental rotation studies provide evidence for analog rather than propositional representation of mental images?
Think about your answer, then reveal below.
Model answer: If mental images were propositional — symbolic descriptions like lists of features — comparing two shapes at different orientations would involve checking descriptions against each other, which should not systematically take longer as angle increases. The linear scaling implies the mind must traverse through intermediate states (as if actually rotating the image), which is a property of analog representation where spatial structure is preserved in the representation itself.
The key is that propositional systems are designed for fast symbolic lookup — they don't have 'intermediate orientations' to pass through. An analog representation, like a physical object being rotated, must pass through every intermediate angle, taking time proportional to the angular distance. The mental rotation data show exactly this signature. Shepard interpreted this as the mind operating on a representation that preserves the geometry of the original object — not just its verbal or symbolic description.