Distraction shrinks space.

Research investigating how people remember the distance of paths they walk has shown two apparently conflicting effects of experience during encoding on subsequent distance judgments. By the feature accumulation effect, discrete path features such as turns, houses, or other landmarks cause an increase in remembered distance. By the distractor effect, performance of a concurrent task during path encoding causes a decrease in remembered distance. In this study, we ask the following: What are the conditions that determine whether the feature accumulation or the distractor effect dominates distortions of space? In two experiments, blindfolded participants were guided along two legs of a right triangle while reciting nonsense syllables. On some trials, one of the two legs contained features: horizontally mounted car antennas (gates) that bent out of the way as participants walked past. At the end of the second leg, participants either indicated the remembered path leg lengths using their hands in a ratio estimation task or attempted to walk, unguided, straight back to the beginning. In addition to response mode, visual access to the paths and time between encoding and response were manipulated to determine whether these factors would affect feature accumulation or distractor effects. Path legs with added features were remembered as shorter than those without, but this result was significant only in the haptic response mode data. This finding suggests that when people form spatial memory representations with the intention of navigating in room-scale spaces, interfering with information accumulation substantially distorts spatial memory.