semicircular canals

a set of three looped tubular channels in the inner ear that detect movements of the head and provide the sense of dynamic equilibrium that is essential for maintaining balance. They form part of the vestibular apparatus. The channels are filled with fluid (endolymph) and are oriented roughly at right angles to each other. Hence, they can monitor movements in each of three different planes. Each canal has an enlarged portion, the ampulla, inside which is a sensory structure called a crista. This consists of hair cells whose fine extensions are embedded in a gelatinous cap (the cupula). When the head moves in a certain plane, endolymph flows through the corresponding canal, displacing the cupula and causing the hairs to bend. This triggers the hair cells to fire nerve impulses, thus sending messages to the brain about the direction and rate of movement.

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Psychology term of the day

May 9th 2024

state space

1. a graphical representation used to characterize game playing and other search-based problem solving. A state space has four components: (a) a set of nodes or states, (b) a set of arcs linking subsets of the nodes, (c) a nonempty set of nodes indicated as the start nodes of the space, and (d) a nonempty set of goal nodes of the space. The goal nodes are identified by either a property of the state itself (e.g., a checkmate) or a property of the path leading to the goal state (e.g., the shortest path). An architecture such as a production system or classifier system can generate a state-space search. Computational state-space analysis and computer simulations of problem solving often are used as well in the study of how people pursue goal-directed behavior. See also graph; search; tree.

2. multidimensional space, particularly as related to the depiction of the results of classification methods used to group objects with similar characteristics and patterns of behavior.