Unit quiz: Sensation as construction: from receptor sheets to perceptual signals

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5 questions · 80% to pass · no timer. This quiz checks the lessons in this unit. These authored questions assess recognition and application of the taught distinctions, not professional qualification. You may review the lessons and retry. Repeat attempts reuse the question bank; a remembered answer is not proof of transfer to a new situation.

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Question 1

A laboratory measures receptive fields in two visual areas and finds that fields in the second area are, on average, four times larger than in the first, with no anatomical tracer work. A reviewer concludes that the two areas form a two-stage hierarchy. What is the strongest objection to that conclusion?Pooling alone enlarges receptive fields, so the size difference could arise from a common input source or from parallel streams rather than from the second area receiving convergent projections from the first.The objection fails because receptive field size is determined by the number of neurons in an area, and a larger area necessarily sits above a smaller one.

Question 2

An engineer designs an auditory prosthesis that estimates source direction by measuring the arrival time of sound at two microphones spaced 0.18 metres apart, and is puzzled that the estimate becomes erratic for high-frequency sounds. Using the physics in the lesson, explain the cause and the design change indicated.The microphones are too close together to register any arrival difference at high frequencies, so the spacing should be increased until the delay exceeds one period at the target frequency.At high frequencies the sound's period becomes shorter than the maximum arrival difference of roughly half a millisecond, so the timing measurement becomes cycle-ambiguous; the indicated change is to use the level difference between the two microphones for high frequencies.

Question 3

A researcher records from a single rapidly adapting mechanoreceptor and finds that it fires twice, at the onset and the offset of a held indentation. She concludes that this afferent is the brain's signal for the duration of contact. Which further result is required before the word signal is doing any work?Evidence about readout, showing that the percept of contact duration follows this afferent's activity when the rest of the population responding to the same contact is held constant or manipulated.A larger sample of the same afferent class, since repeating the recording in more units would establish that the afferent class carries the duration signal.

Question 4

Two people receive identical stimuli to identical skin sites in a controlled experiment and report pain that differs by more than a factor of two. One researcher says the difference must be measurement noise. Using the double pain and modulation evidence, evaluate that response.It is sufficient, because identical stimuli must produce identical nociceptor activity and therefore identical pain, so any difference is error.It is not sufficient as an explanation, because the same peripheral input can produce different transmission depending on converging afferent and descending inputs, so a large between-person difference is an expected property of the system that requires a design that varies modulation rather than an appeal to noise.

Question 5

A device reports head orientation by integrating the signal from a sensor that measures angular acceleration and whose output decays with a five-second time constant. After about fifteen seconds of steady rotation the reported orientation has drifted far from the true value. What does this demonstrate about the sense the device is imitating?That an acceleration signal must be combined with other evidence, such as gravity-referenced or visual signals, because integration of a decaying signal cannot sustain a position estimate during prolonged motion.That the sensor is faulty, since a correctly functioning position sensor would not produce drift over fifteen seconds of steady motion.

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