Direct manipulation of perceived angular declination affects perceived size and distance: a replication and extension of Wallach and O’Leary (1982)

In two experiments involving a total of 83 participants, the effect of vertical angular optical compression on the perceived distance and size of a target on the ground was investigated. Replicating an earlier report (Wallach & O’Leary, 1982), reducing the apparent angular declination below the horizon produced apparent object width increases (by 33 %), consistent with the perception of a greater ground distance to the object. A throwing task confirmed that perceived distance was indeed altered by about 33 %. The results are discussed in relation to cue recruitment and to recent evidence of systematic bias in the perception of angular declination.