Core distinction and conditions
Perception involves interpretation and organization of sensory input, with influences from stimulus features and prior knowledge or task demands. Gestalt grouping principles describe different relations: proximity concerns spatial closeness, while similarity concerns shared features. A display can support more than one cue at once. Therefore, when interpreting a comparison, ask which feature changed and which features were held constant. Naming a principle is less informative than explaining why that principle accounts for the stated contrast and whether another cue has been introduced alongside it.
Worked example: make the competitor visible
Suppose identical symbols are arranged in two nearby rows with a large gap between rows. Spatial closeness supports grouping by row. If the symbols in each row are then given a shared shape that differs across rows, similarity now favors the same grouping. The outcome alone cannot isolate spacing from the added feature cue. A uniform change to the shape of every symbol would be different: it would not create a row-specific similarity contrast. This comparison uses verbally specified features and does not claim that a diagram is required to answer a question whose necessary conditions are already given in text.
Attention and constancy answer different questions
A person focused on counting one kind of event may fail to notice another visible event. If the unchanged video is later viewed without that demand, the event may be reported. This illustrates an attentional limit and does not establish that the event was physically absent. Constancy concerns another relation: attributed object properties can remain roughly stable despite changing sensory projections. A moving object can occupy less retinal area while being perceived as about the same size. That stability does not mean the image itself stayed constant, or that distance cues were ignored. Keep the input, the task and the perceived property on separate lines.
Transfer check: test an alternative account
A designer changes both color and spacing so each nearby group has its own color. Can a grouping response be attributed specifically to proximity? Not from that contrast alone, because similarity also varies. Describe a comparison that keeps the feature cue constant while changing spacing. Next, explain why not reporting an event under a demanding counting task does not prove it was below an absolute threshold. Finally, name the difference between a shrinking retinal projection and a roughly stable size estimate. These checks assess the stated distinctions, without claiming complete coverage of perception or an invariant result for all observers.
Try it, then explain it.
Complete a short set without looking at the example. After each answer, explain which evidence or rule supports your decision and why the alternatives do not fit.
Sources & authorship
Original OpenExam explanations and examples. References support the concepts; they are not the source of copied questions. Independent educator review is pending.
OpenStax Psychology 2e, section 5-6OpenStax Psychology 2e, section 5-1College Board AP Psychology ced