Affording Design, Affording Redesign - Principia Designae: Pre-Design, Design, and Post-Design - page 87

marks on a page as well as location on a page also carry meaning. Larger marks
indicate larger thing. Larger marks also attract more attention, and size is used to
indicate importance. Closer in paper space suggests closer in conceptual space.
Sketching or diagramming ideas make abstract ideas concrete, hence easier to
conceptualize. Putting ideas on a page promotes inferences based on spatial rea-
soning, proximity, direction, distance as surrogates for more difficult abstract
reasoning. Crucially, for designers of any kind, sketches invite not just organization
but also reorganization, easy trial and error (Tversky 2011a ).
Design is nothing if not full of paradoxes and contradictions. Divergent and
convergent thinking are at its core. The new and the old. Letting the mind wander
and focusing it. Similarly, any tool, cognitive or physical, has disadvantages as well
as advantages and many of the disadvantages are their very advantages. Sketches
make the abstract concrete, and thereby force concreteness, promoting concrete
spatial thinking. They structure and organize, thereby forcing premature specificity
Putting ideas on a page can enable thought but also can constrain thought in ways
that may have nothing to do with the problem at hand. Interacting effectively with
sketches and diagrams requires expertise, to make the concrete abstract again, to
see abstract implications in concrete spatial relations, to reconfigure configurations.
7.2 Designing Sketches: Sketches Reveal Thought
Sketches are exactly that, sketchy, schematic. They give an idea of what a designer
has in mind, but they are inexact and incomplete, blobs for entities, like buildings,
rough lines for relationships, like paths. They omit detail that hasn't been worked
through or that is not relevant. In emphasizing the essential aspects of the design they
not only simplify, they may exaggerate and distort. In so doing, they can reveal the
underlying representation or model the designer has in mind. The schematic nature
of diagrams also suggests possibilities, invites inferences, and enables revisions.
7.2.1 Sketch Maps
Maps are one of the commonest uses of sketches, by everyone. Although maps,
even sketch maps, could be analog, people's sketch maps of regions or routes
typically straighten curved roads and make streets more parallel and perpendicular.
Just as they don't pay much attention to angle, they don't pay much attention to
distance, often compressing large distances with few choice points or other infor-
mation and enlarging small ones containing many choice points or other informa-
tion. They reduce large complex environments not just in size but also in detail,
including only detail of relevance (e.g., (Fontaine et al. 2005 ; Lynch 1960 ; Taylor
and Tversky 1992 ; Tversky 2001 ) ). Route maps get further simplified; they typi-
cally include only the relevant path (Tversky 2011b ; Tversky and Suwa 2009 ) .