Where does reflection collide?

In optics, reflection is the change in direction of a wavefront at an interface between two media, so that part or all of the wave returns into the medium from which it came. For a smooth surface the law of reflection holds, the angle of reflection equalling the angle of incidence measured from the normal, giving mirror-like or specular return, while a rough surface scatters the wave into many directions as diffuse reflection. Hecht's Optics derives these relations from the wave and electromagnetic treatment of light, and Nicodemus formalised how the reflected radiance of an opaque surface depends on the directions of illumination and view. The referent is a physical redirection of radiation at a boundary, measured as a reflectance or albedo, not a person examining their own experience, a program reading its own code, or a mind turning upon its ideas.[1][2]

Unit

A wavefront's redirection at an interface, as the fraction of incident power reflected

Recovery means

Not applicable

Measured by

Quantified by reflectance and albedo, and by goniometric measurement of the reflected radiance against angle

In professional education, reflection, or reflective practice, is the deliberate examination of one's own experience in order to learn from it and improve future action. Schön distinguished reflection-in-action, the thinking a practitioner does while an activity is still under way, from reflection-on-action, the later review of what happened and why, extending Dewey's earlier account of reflective thought. The referent is a disciplined mental and often written activity by which a nurse, teacher, or engineer interrogates their own judgements, not a beam of light returning from a surface, a program examining its own structure, or a chapter in Locke's epistemology.[3]

Unit

A structured review of one's own practice, in reflective episodes or journal entries

Recovery means

Not applicable

Measured by

Assessed through reflective journals, portfolios, and rubrics that rate the depth of reflection

In computer science, reflection is a program's ability to inspect and modify its own structure and behaviour while it is running: to examine its types, objects, and code as data, and to act on them. Smith's account of procedural reflection in Lisp gave the idea a precise footing, describing a language whose programs can reason about and alter their own interpretation, and the term now spans introspection and metaprogramming across languages such as Java, Python, and Lisp. The referent is a computational self-representation manipulated at runtime, not light returning from a mirror, a professional reviewing their practice, or the mind's awareness of its own ideas.[4]

Unit

A program's runtime access to its own structure, exposed through a reflection API

Recovery means

Not applicable

Measured by

Exercised through introspection and metaobject interfaces that expose types, fields, and methods at runtime

In Locke's philosophy, reflection is one of the two fountains from which all our ideas spring: alongside sensation, which supplies ideas of outer things, reflection is the mind's perception of its own operations, such as perceiving, thinking, doubting, and willing. Locke described it as a kind of inner perception by which the understanding turns upon itself and takes notice of what it does, so that ideas of the mental acts themselves become available to thought. The referent is an epistemic faculty of inner observation, posited to explain where certain ideas come from, not a physical return of light, a practitioner's review of their work, or a program reading its own code.[5]

Unit

The mind's inward perception of its own operations, as a source of ideas

Recovery means

Not applicable

Measured by

Not directly measured; it is a philosophical faculty argued for by analysis of the origin of ideas, not an empirical quantity