High-capacity, transient retention of direction-of-motion information for multiple moving objects

Abstract

The multiple-object tracking paradigm (MOT) has been used extensively for studying dynamic visual attention, but the basic mechanisms which subserve this capability are as yet unknown. Among the unresolved issues surrounding MOT are the relative importance of motion (as opposed to positional) information and the role of various memory mechanisms. We sought to quantify the capacity and dynamics for retention of direction-of-motion information when viewing a multiple-object motion stimulus similar to those used in MOT. Observers viewed three to nine objects in random linear motion and then reported motion direction after motion ended. Using a partial-report paradigm and varying the parameters of set size and time of retention, we found evidence for two complementary memory systems, one transient with high capacity and a second sustained system with low capacity. For the transient high-capacity memory, retention capacity was equally high whether object motion lasted several seconds or a fraction of a second. Also, a graded deterioration in performance with increased set size lends support to a flexible-capacity theory of MOT.

Why do people appear not to extrapolate trajectories during multiple object tracking? A computational investigation

“…Specifically, making conservative predictions is consistent with work demonstrating that observers are sensitive to and can report object bearing accurately, on average, but with a great deal of noise in many situations (Horowitz & Cohen 2010;Shooner et al, 2010;St. Clair et al, 2010).…”

“…In particular, several studies have shown that human observers possess the raw materials necessary for extrapolation. They can report (albeit with noise) the direction of a target's motion in an MOT trial (Horowitz & Cohen, 2010;Iordanescu, Graboweky, & Suzuki, 2009;Shooner, Tripathy, Bedell, &Ögmen, 2010). One study even demonstrated that a moving pattern within an object can impair tracking if it moves against the object's trajectory, suggesting an automatic encoding of bearing (St. Clair, Huff, & Seiffert, 2010) and a cost caused by signals that make this encoding difficult.…”

Speed has an effect on multiple-object tracking independently of the number of close encounters between targets and distractors

“…Greater allocation of the attentional enhancement resource to a target might result in greater precision of target localization (Alvarez & Franconeri, 2007) and greater precision of motion direction representation, which would facilitate tracking the target. Both precision of target localization (Howard & Holcombe, 2008) and motion direction representation Shooner, Tripathy, Bedell, & Öğmen, 2010) in MOT have been found to decrease with increased number of targets, and precision of target localization has been found to decrease with increased speed (Howard, Masom, & Holcombe, 2011). These findings suggest that the precision of these representations is dependent on a limited resource.…”

Normal Aging Delays and Compromises Early Multifocal Visual Attention during Object Tracking

“…Tracking tasks that involve the detection of deviations of motion trajectories depend on sensory memory of the motion trajectory, as they require the comparison of a current motion direction to the just-observed motion direction (Narasimhan, Tripathy, & Barrett, 2009). Possibly, such memory traces also play a role during classic MOT tasks (Shooner, Tripathy, Bedell, & Ogmen, 2010). Prominent age-related declines, starting at age 30, have been observed in the ability to detect deviations of linear motion trajectories in the absence of distractor objects (Kennedy, Tripathy, & Barrett, 2009).…”