The One-is-More Illusion



Here are some demonstrations of various conditions discussed in the following paper:
Yousif, S., & Scholl, B. J. (2019). The one-is-more illusion: Sets of discrete objects appear less extended than equivalent continuous entities in both space and time. Cognition, 185, 121-130.
These demonstrations are provided as MP3 or MP4 files, which can be downloaded or played directly in most web-browsers. As highly compressed versions of the original stimuli, these files may not preserve the precise characteristics of the originals.  
 
We distinguish between discrete objects and continuous entities in categorization and language, but might we actually see and hear such stimuli differently? In this paper we report the one-is-more illusion, wherein 'objecthood' changes what we perceive in an unexpected way. Across many variations and tasks, observers perceived a continuous object (e.g. a rectangle) as longer than equated discrete objects (e.g. two shorter rectangles separated by a gap). This illusion is phenomenologically compelling, exceptionally reliable, and it extends beyond space, to time: a continuous tone is perceived to last longer than an equated set of discrete tones. Previous work has emphasized the importance of objecthood for processes such as attention and visual working memory, but these results typically require careful analyses of subtle effects. In contrast, we provide striking demonstrations of how perceived objecthood changes the perception of other properties in a way that you can readily see (and hear!) with your own eyes (and ears!).  
 
The static visual demonstrations are provided as figures in the paper itself, but this page hosts the relevant auditory/temporal demos and the one visual demo that involves a dynamic animation:  
 
Demonstration 1: Tones (with Explanation) (1.8 MB)
Demonstration 1: Tones (Stimuli only) (168 KB)
A single continuous tone is contrasted with two discrete tones separated by a brief silence. From start to finish, both stimuli are equally long -- but the single continuous tone is perceived as lasting considerably longer.  
 
Demonstration 2: Temporal Occlusion (with Explanation) (1.6 MB)
Demonstration 2: Temporal Occlusion (Stimuli only) (116 KB)
To equate the amount of actual auditory stimulation, this demonstration contrasts two tone fragments that are interrupted either by a brief silence (making them sound like two discrete tones) or by a burst of auditory noise (making them sound like a single tone that continues through the 'auditory occluder'). From start to finish, both stimuli are again equally long -- but the stimulus with the tone that is heard to continue through the auditory occlusion is perceived as lasting considerably longer.  
 
Demonstration 3: Occluded Motion (1.2 MB)
Most of the visual demonstrations of the one-is-more illusion are provided as figures in the manuscript, but there is one that involves a dynamic animation. Here, the two 'pieces' of a rectangle move next to a stationary occluder. On the top, the pieces move together, such that they are perceived as a single object; on the bottom, the pieces move in the same general manner, but asynchronously, such that they are perceived as two separate objects. As a result, the spatial extent of the whole -- from the leftmost point of the left 'piece' to the rightmost point of the right 'piece' -- appears longer in the version on the top, even though these extents are in fact equated.