"The Conditions of Learning" book is written by

Concept: A well-known instructional-design framework classifies learning into five distinct outcome categories — verbal information, intellectual skills, cognitive strategies, motor skills, and attitudes — and specifies the internal conditions (previously learned prerequisite capabilities) and external conditions (instructional events) required for each type to occur. A landmark 1965 book carrying this exact title laid out this framework.

Application: The question asks which of the listed psychologists authored this book. Among the four names offered, only Robert M. Gagné is credited with originating this outcome-and-conditions framework and authoring the 1965 work "The Conditions of Learning" — the same title the question names — while the other three are associated with entirely different theories.

Distractors ruled out:

• Ivan Pavlov's contribution is classical conditioning, demonstrated through stimulus-response pairing in salivation-reflex experiments — a different line of work from cataloguing learning-outcome types and their conditions.

• B.F. Skinner's contribution is operant conditioning and reinforcement scheduling, studied through devices such as the Skinner box — again a distinct strand from this book's outcome-and-conditions framework.

• E.L. Thorndike's contribution is connectionism and the Law of Effect, derived from trial-and-error learning experiments — not the source of this particular instructional-design treatise.

Cross-check: the book's title directly names its subject — the conditions under which each type of learning occurs — which matches the author's broader body of work on instructional systems design and the nine events of instruction built on this same framework.