The five experiments presented demonstrate that action video game play increases the number items that can be enumerated and tracked simultaneously over time. In Section 2, habitual action video game players display enhanced enumeration accuracy as compared to non-players. Section 3 establishes a causal role for action video game play, as NVGPs specifically trained on an action video game show similar enhancements. Section 4 demonstrates for the first time a dissociation between accuracy and reaction time measures of the subitizing range and establishes that action game playing does not modify the number of items that can be immediately apprehended, but rather enhances accurate counting. By making use of the multiple object tracking paradigm, Section 5 demonstrates an effect of VGP status on the ability to simultaneously track multiple objects over an extended period of time. The significant improvement in MOT performance seen in NVGPs after action game training in Section 6 demonstrates that action video game playing has a causal role in the measured effects.
Taken together, these five experiments suggest that action video game play may enhance some aspects of visual working memory. Several lines of evidence point to this conclusion. First, VGPs demonstrate enhanced enumeration accuracy even at very high numerosities. Second, this enhanced accuracy is accompanied by an increase in RTs. Although this pattern would be the expected speed/accuracy trade-off in a system in which evidence accumulates over time but does not decay, the behavior under study relies on visual short-term memory in which representations are known to decrease in fidelity over time (Lee & Harris, 1996
; Nilsson & Nelson, 1981
; Sperling, 1960
; Vogels & Orban, 1986
). Delaying responses in studies of short-term memory does not lead to increased accuracy, but rather decreased accuracy as the memory representations have more time to fade. Thus, an alternative explanation seems warranted in which video game experience leads to enhancements in some aspect(s) of visual short-term memory. At least two alternatives are possible, one based on the durability of the memory trace and another on the speed of cycling through the memory trace. In the first case, action video game experience may lead to a more durable visual memory trace. This view would be consistent with the accuracy and reaction time data as well as the average response data where NVGPs begin to underestimate the number of squares well before the VGPs. One may speculate that after a certain period of time, NVGPs begin to ‘drop’ items from visual memory, and at this point they simply make their best guess (from viewing and , one can surmise that the NVGPs RTs appear to plateau at around eight items). Conversely, if it were the case that VGPs possess a more durable memory trace, they would be able to continue counting beyond the point where the NVGPs have stopped, which would account for both the greater accuracy and longer RTs. In addition, this process may also sustain better tracking ability in the MOT by allowing more durable indexing of the dynamics of the objects to be tracked. However, a change in the fidelity of working memory representations in gamers is only one possible explanation for the observed results. A possible alternative hypothesizes that items in working memory are not necessarily kept simultaneously active, but instead one or a few items are constantly refreshed by a visit from a single focus of attention that moves from item to item in a cyclical fashion. As the speed of cycling through the items increases, the number of items that could be successfully maintained in short term memory would correspondingly increase. It is therefore possible to capture the present findings by assuming that the speed of cycling through memory traces is faster in VGPs than NVGPs, thus accounting for both the better counting and multiple object tracking performance. It should be further noted that factors unrelated to visual short-term memory, such as estimation ability and response bias, may also be at work in the enumeration paradigm, particularly for high numerosities. For instance, VGPs may be better able to judge when ‘the most’ number of squares were presented, without necessarily being able to explicitly count each item. Also, as previously mentioned, because the maximum response was capped at some maximum value, a bias toward underestimation for the larger numerosities is created that may not be exactly equal in the two populations. A role for these differences in estimation/bias cannot be ruled out in interpreting some of the current results, especially at high numerosities, but they remain an unlikely explanation at lower numerosities where the accuracy breakpoint is seen to shift between NVGPs and VGPs.
Beyond the effect of action video game play, these findings also lend strong support to models of enumeration performance that propose relatively distinct constraints for the two components of the enumeration performance curve. The dissociation between the accuracy and RT breakpoints in gamers is probably the most robust indication to-date of separate mechanisms, one that is sensitive to gaming (counting) and one that is not (subitizing). Similarly, the comparison of two different fields of view in Section 2 indicates that the mechanism(s) behind subitizing are less malleable that those behind counting. Indeed, in Section 2, performance over the subitizing range was quite similar across visual field conditions. Only in the counting range did performance differ with more accurate performance for the smaller field of view and denser displays. Models that suppose fundamental differences in the characteristics of the display (density, patterns, etc.) between low and high numerosity stimuli cannot readily account for the overall pattern of results reported here, be it the effect of gaming or that of visual field size. Models of enumeration studies which posit two separate mechanisms—a fast and parallel one for subitizing and a more serial process for counting-more naturally capture the main findings. Under this view, the mechanism underlying subitizing would show little to no sensitivity to gaming or visual field size, and be highly specific to the enumeration of low numerosities. In contrast, the mechanism underlying counting would be much more plastic, showing enhancement with gaming and be facilitated by the use of a small visual field.
Although some have suggested a link between immediate apprehension in the enumeration task and performance on the MOT paradigm (for instance, that they may both utilize preattentive mechanisms, or FINSTs—Pylyshyn, 1989
; Trick & Pylyshyn, 1994
), our results suggest that the subitizing range does not index the same process as the MOT. VGPs demonstrate no enhancement in subitizing range as measured by RT, but do demonstrate an enhancement in MOT ability. Also, while there is virtually no cost in terms of speed or accuracy moving from one to three items in the enumeration paradigm, a clear decrease in accuracy is observed with each additional item in the MOT paradigm (even moving from one to two items). Thus, it appears that the number of items that can be immediately apprehended as measured by RT measures in enumeration studies is not necessarily a good predictor of the number of items than can be simultaneously tracked. Although our data do not allow us to draw strong conclusions, our findings suggest that the number of items that can be accurately counted may be a better correlate of tracking capabilities, as both of these measures are found to improve with gaming.
This study establishes that when it comes to the number of objects that can be attended, a distinction should be drawn between a fast, parallel behavior that displays little plasticity and a more serial behavior that displays a range of plastic behaviors. As such these studies make several contributions, both to our understanding of the processes indexed by the enumeration and MOT paradigms, as well as to our understanding of the nature of the changes that occur as a result of action video game play. It will be, however, for future experiments to fully characterize the consequences of these results for models of attention and working memory.