Contiguity 

con·ti·gu·i·ty :  the state of bordering or being in direct contact with something.
"nations bound together by geographical contiguity"

con·ti·gu·i·ty
/ˌkän(t)əˈɡyo͞oədē/

noun
the state of bordering or being in direct contact with something.
"nations bound together by geographical contiguity"
PSYCHOLOGY
the sequential occurrence or proximity of stimulus and response, causing their association in the mind.