Signifiers

Definition: A signifier is any perceivable mark or sound — any indicator — that communicates appropriate behavior to a person. It tells where and how to act. Norman's key addition to the 2013 edition (borrowed loosely from semiotics; first used in his Living with Complexity).

Core distinction (the book's most quoted line):

Affordances determine what actions are possible. Signifiers communicate where the action should take place. We need both.

Properties:

• Signifiers must be perceivable, else they fail.
• Can be deliberate (a "push" sign, an arrow on a touchscreen) or accidental/incidental (a worn path across a field; a bookmark's position signaling pages remaining; people waiting → train not yet gone).
• A perceived affordance (a handle, a switch shape) can be a signifier — but may be misleading (fake doors; rubber posts that look like an anti-affordance but let authorized vehicles through).
• When a simple object (a door) needs an added sign ("push"/"pull") to be understood, that is a marker of bad design.

Why more important than affordances

Affordances are relationships and confusing for virtual objects; designers need a word for "the thing that signals what to do." That is the signifier. For the most part, designers can focus on signifiers. See the Socratic "Affordances and Signifiers: A Conversation" (ch.1).

Confidence

1.0 — explicitly defined and contrasted at length.

Sources: ["DOET ch.1 'Signifiers' p.13-19; preface"]