Visual short-term memory is an inherently capacity-limited system; however, the present results support the potential malleability of this system. We confirmed a previous finding that individuals with extensive experience playing action video games have enhanced VSTM for briefly presented stimuli, as compared to individuals who did not play action games (Boot et al., 2008). Extending previous findings, AVGPs displayed a VSTM advantage, regardless of whether limited or ample time was given to encode the initial memory array (i.e., 168 vs. 1,018 ms) and of the complexity of the to-be-stored items (i.e., colored squares vs. complex shapes). Thus, whereas previous studies have demonstrated that AVGPs’ faster processing of visual information affords them benefits in a number of tasks (Dye et al., 2009b), it does not appear to account for their VSTM advantage.
Our results showed no evidence for an interaction between encoding duration and group, which suggests that the amount of time given to encode the memory items did not alter the degree of the advantage that AVGPs demonstrated over NVGPs. Given the existing literature on VSTM consolidation timing, it seems unlikely that using a longer encoding duration (i.e., >1,018 ms) would have allowed the NVGP group to “catch up” and equate their performance with the AVGPs. Previous work has illustrated that the average amount of time required to consolidate a simple colored item into VSTM is approximately 50 ms (Vogel et al., 2006), suggesting that our long encoding duration of 1,018 ms provided more than ample time for individuals to encode up to six items in Experiment 1. Furthermore, our use of more complex shapes in Experiment 2 demonstrated that AVGPs’ VSTM advantage is still similarly unaffected by encoding duration when the perceptual load of the to-be-stored items is increased. As expected, the complex shapes used in Experiment 2 increased the difficulty of the VSTM task. Notably, both groups appeared similarly less able to encode and store the complex shapes, relative to the simple colored squares, with the decrements to performance appearing to be similar across the groups. Thus, the use of even more complex shapes or an even longer encoding duration would be unlikely to change our findings.
Our results are inconsistent with those of Wilms et al. (2013), who found increased speed of processing for AVGPs and attributed that speed of processing to faster encoding of information into VSTM. The main difference between their study and the present one was the encoding durations used. Wilms et al. used 50- and 100 ms encoding durations. However, it seems unclear why they did not find a capacity advantage for their AVGP group using a 100 ms encoding duration, as this is the same encoding duration used by Boot et al. (2008), who did find a VSTM advantage. Furthermore, given the evidence that the average consolidation time for simple colored stimuli like those used in Experiment 1 is 50 ms (Vogel et al., 2006), the encoding duration used in Experiment 1—that is, 168 ms—should have been sufficiently short to reveal any effect, if one was present, of an encoding speed advantage on AVGPs’ VSTM performance. Furthermore, in Experiment 2 we used the same encoding duration, but with more complex stimuli that one might assume would require additional time to encode into VSTM, but still we failed to reveal evidence of the contribution of an encoding speed advantage to AVGPs’ enhanced VSTM performance. However, the present study cannot speak directly to potential contributions of encoding speed to AVGPs enhanced VSTM under shorter encoding durations (i.e., <168 ms), such as those used in the Wilms et al. study. Notably, Wilms et al.’s failure to find a VSTM advantage under these conditions puts in question the potential of such data to provide insight into the sources of the VSTM advantage amongst AVGPs (documented here and elsewhere; Boot et al., 2008). Taken together, the results of the present study and of previous studies (Boot et al., 2008; Clark et al., 2011; Green & Bavelier, 2006b; Sungur & Boduroglu, 2012; Wilms et al., 2013) suggest that AVGPs do possess a VSTM advantage; however, the relationship between VSTM capacity and speed of encoding may be complex and may vary under differential task conditions.
One potential limitation to our results may be the use of the same participants across both experiments. By using the same group of AVGPs and NVGPs in Experiment 2, the replication of findings from Experiment 1 is perhaps not surprising in some respects. However, the stability of AVGPs’ VSTM advantage across the two experimental sessions and despite the change in the complexity of the stimuli used provides further support for the robustness of a VSTM advantage among AVGPs. Furthermore, using the same participants allowed us to demonstrate the stability of VSTM performance differences at an individual level, even when the testing sessions occurred on average approximately 102 days apart and assessed VSTM for different stimulus dimensions (i.e., color vs. shape). Notably, to our knowledge, the stability of effects over time has not been previously demonstrated in the video gaming literature.
Previous work on VSTM capacity has suggested that individual differences may emerge at large set sizes due to the greater need for selectivity and control of attention (e.g., Fukuda & Vogel, 2009; Herrero, Nikolaev, Raffone, & van Leeuwen, 2009; Kuo, Stokes, & Nobre, 2012; Vogel, McCullough, & Machizawa, 2005). Considering the previously discussed attentional findings in the action video game literature (e.g., Bavelier et al., 2012), it may be that enhanced selective attention underlies AVGPs’ VSTM advantage. Indeed, Green and Bavelier (2012) suggested that the underlying mechanism of AVGPs’ visuo-cognitive advantages may be increased abilities to select task-relevant and to ignore task-irrelevant visual information via augmented attentional control and executive functioning. They suggested that action video games foster an increased ability to flexibly and effortlessly allocate attentional and executive resources in visuo-cognitive tasks. This notion of enhanced selective attention underlying AVGPs’ visuo-cognitive advantages is consistent with our finding in Experiment 1 that AVGPs showed a greater VSTM advantage at the largest set size. Furthermore, whereas a significant Group × Set Size interaction did not emerge in Experiment 2, examination of Fig. 4 illustrates a trend toward a larger advantage for AVGPs at set size 4 than at set sizes 1 and 2. Given that only set size 4 represented a supracapacity set size in Experiment 2, these results are consistent with those of Experiment 1 and suggest that enhanced selective attention may contribute to this VSTM advantage. Additional studies will be needed in order to more directly explore the potential role of superior attentional control in contributing to the AVGPs’ VSTM advantage documented here.
Notably, the VSTM advantage demonstrated here amongst AVGPs, relative to NVGPs, is unlike some other previously reported experience-based VSTM advantages, such as that for faces and other objects of expertise (Curby & Gauthier, 2007; Curby et al., 2009; Scolari, Vogel, & Awh, 2008). In addition to its domain-specific nature, the VSTM advantage reported for faces and nonface objects of expertise was dependent on encoding time, with the VSTM advantage emerging with extended encoding time, suggesting that experts, if given enough time, can more efficiently store complex objects that lie within their domain of expertise (Curby & Gauthier, 2007). In contrast, the VSTM advantage among AVGPs appears to be domain-general, to be equally present under brief and extended encoding durations, and to be unaffected by the visual complexity of the stimuli to be stored. Thus, the present findings, in the context of previous work documenting VSTM advantages for objects of expertise, highlight that experience might impact VSTM in multiple ways. Furthermore, the present study has focused on the notion that a VSTM advantage for AVGPs translates to greater capacity, or at least a greater estimate of capacity, as measured by performance in our change detection tasks. However, much debate still focuses on the influences of capacity versus resolution with regard to differences in performance on change detection tasks (e.g., Alvarez & Cavanaugh, 2004; Bays, Catalao, & Husain, 2009; Bays & Husain, 2008; Luck & Vogel, 1997). It may be that AVGPs’ VSTM advantage is more akin to an advantage in the precision with which items are stored in VSTM (Sungur & Boduroglu, 2012). Regardless, these findings, in addition to those in the expertise literature, suggest that visual experience can influence VSTM in multiple ways.
A potential limitation to the present study is the use of overt recruitment. According to Boot, Blakely, and Simons (2011), cross-sectional studies should engage in covert recruitment in order to avoid differential demand characteristics and motivation levels between gamers and nongamers. It may be possible that our explicit recruitment of “individuals with a range of video game experience” biased our AVGP group in some way that differed from our NVGP group. However, there is no empirical evidence to support the notion that overt recruitment leads to differential motivation in AVGPs and NVGPs at this point in time. This will be a critical avenue for future research, as this body of literature expands.
Whereas the VSTM advantage for AVGPs reported here builds on the existing literature regarding enhanced visuo-cognitive abilities resulting from extensive action video game playing (Bavelier et al., 2012; Chisholm et al., 2010; Clark et al., 2011; Dye, Green, & Bavelier, 2009a, b; Feng et al., 2007; Green & Bavelier, 2003, 2006a, 2006b, 2007; Green, Sugarman, Medford, Klobusicky, & Bavelier, 2012; Mishra, Zinni, Bavelier, & Hillyard, 2011; Sungur & Boduroglu, 2012; West, Stevens, Pun, & Pratt, 2008), it is worth noting that the effect sizes found in our study are relatively small in comparison to those in other cross-sectional studies. Although AVGPs display a VSTM advantage over NVGPs, this advantage appears to be less pronounced than some of the attentional and perceptual benefits found in the literature. It is also possible that a selection bias (i.e., individuals with high VSTM capacity may be more likely to play action video games initially) may contribute to this VSTM advantage observed among AVGPs. Training studies, in which nongamers are recruited and randomly assigned to train on action video games or a control game, are typically used in this literature to avoid self-selection biases that might be at play in real-world AVGP and NVGP groups. Notably, although Boot et al. (2008) did not find a training effect on VSTM after 21.5 h of training, a more recent study suggests that 20 h of action video game play is sufficient to improve VSTM, as evidenced by increased change detection performance relative to a control group (Oei & Patterson, 2013). Although the present study cannot attest to the causal effect of action video game play on VSTM, these mixed findings from training studies warrant further investigation into the relationship between action video game play and VSTM performance.
In summary, action video games provide the player with a complex and constantly changing visual environment in which efficient visual attention and accurate visual memory often determine the player’s success or failure in the game. From the present results, exposure to these visual environments over an extensive period of time appears to enhance this capacity-limited VSTM system. Thus, video game playing could serve as a useful tool for enhancing VSTM performance in a domain-general manner. The importance of VSTM in acquiring knowledge from the visual environment renders the potential to enhance VSTM through training an important avenue for further research.