Can sequencing of articulation ease explain the in-out effect? A preregistered test

Words whose consonantal articulation places move from the front of the mouth to the back (e.g. BADAKA; inward) receive more positive evaluations than words whose consonantal articulation places move from the back of the mouth to the front (e.g. KADABA; outward). This in-out effect has a variety of affective, cognitive, and even behavioural consequences, but its underlying mechanisms remain elusive. Most recently, a linguistic explanation has been proposed applying the linguistic easy-first account and the so-called labial-coronal effect from developmental speech research and phonology to the in-out effect: Labials (front) are easier to process than coronals (middle); and people prefer easy followed by harder motor components. Disentangling consonantal articulation direction and articulation place, the present three preregistered experiments (total N = 1012) found in-out effects for coronal-dorsal (back), and labial-dorsal articulation places. Critically, no in-out effect emerged for labial-coronal articulation places. Thus, the in-out effect is unlikely an instantiation of easy first.