nictitating membrane

a fold of transparent or semitransparent membrane, present in many vertebrates, that can be drawn laterally over the eye like a third eyelid, independently of the other eyelids. This “blink” (the nictitating-membrane response) can be conditioned in a nonhuman animal (e.g., a rabbit) by pairing a puff of air (the unconditioned stimulus) with a light or tone (the conditioned stimulus).

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Psychology term of the day

January 28th 2025

thermoanesthesia

1. loss or absence of the ability to distinguish between heat and cold by touch.

2. insensitivity to heat. Also called thermanesthesia.