How many objects can you track? Evidence for a resource-limited attentive tracking mechanism.

By George A. Alvarez, Steven L. Franconeri. 2007

492 citations recorded by the source corpus.

Much of our interaction with the visual world requires us to isolate some currently important objects from other less important objects. This task becomes more difficult when objects move, or when our field of view moves relative to the world, requiring us to track these objects over space and time. Previous experiments have shown that observers can track a maximum of about 4 moving objects. A natural explanation for this capacity limit is that the visual system is architecturally limited to handling a fixed number of objects at once, a so-called magical number 4 on visual attention. In contrast to this view, Experiment 1 shows that tracking capacity is not fixed. At slow speeds it is possible to track up to 8 objects, and yet there are fast speeds at which only a single object can be tracked. Experiment 2 suggests that that the limit on tracking is related to the spatial resolution of attention. These findings suggest that the number of objects that can be tracked is primarily set by a flexibly allocated resource, which has important implications for the mechanisms of object tracking and for the relationship between object tracking and other cognitive processes.

Subfields: Cognitive Neuroscience, Computer Vision and Pattern Recognition

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Citations in the corpus

On the Binding Problem in Artificial Neural Networks (2020, background): “The more objects need to be represented simultaneously, the more difficult it is to prevent cross-talk from corrupting and destabilizing individual representation, and such gradual decay has indeed been observed in Alvarez and Franconeri (2007).”
Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults (2009, background): “A second hypothesis, motivated by studies of object-directed attention in adults (e.g., Alvarez & Franconeri, 2007), can account for this effect: representations of distinct objects may compete for attention, reducing the precision of each object representation as the number of other objects in the…”
A taxonomy of external and internal attention. (2011, unknown): “Visuospatial and attentional resolution also strongly affects tracking performance (Alvarez & Franconeri 2007).”
Multiple-object tracking in children: The "Catch the Spies" task. (2005, result): “This is consistent with a recent study on young adults that suggests that there may be differences in the number tracked based on display conditions ( Alvarez & Franconeri , 2004 ) .”
Eye tracking assisted extraction of attentionally important objects from videos (2015, background): “Previous studies have indicated that humans can track upto four objects reliably [5, 20] in video sequence.”
Understanding consumers' in-store visual perception: The influence of package design features on visual attention (2013, background): “Alvarez and Franconeri (2007) argued that the capacity was in fact flexible depending on the allocated resources, the noise and dynamics of the situation.”
Attentional Resource Allocation in Visuotactile Processing Depends on the Task, But Optimal Visuotactile Integration Does Not Depend on Attentional Resources (2016, background): “Given results of other studies in which a systematic relationship was found for increases in attentional demands and task performance (e.g., see Alvarez and Franconeri, 2007; Alnæs et al., 2014), we do think this assumption is reasonable as well.”