The lengthening effect revisited: a reply to Prinzmetal and Wilson (1997) and Masin (1999).

In the present study, the lengthening phenomenon (Tsal & Shalev, 1996), namely, the increase in perceived length of unattended lines, was reexamined in light of criticisms by Prinzmetal and Wilson (1997) and Masin (1999). Prinzmetal and Wilson suggested that the effect was not due to attentional factors but to the spatial interaction between the attended line and the cue used to direct attention. We have replicated the lengthening effect when both attended and unattended lines are preceded by cues at a nearby location, showing that the effect is not caused by spatial cues per se, but instead reflects an inherent property of the attentional system. Masin argued that the lengthening effect is not robust, because it occurs for some but not for all participants. In the present study, the lengthening effect was highly reliable, occurring for each participant for a variety of line lengths.