The UFOV task (Ball et al., 1988
; Ball & Owsley, 1992
; Goode et al., 1998
; Mazer, Sofer, Korner-Bitensky, & Gelinas, 2001
; Myers, Ball, Kalina, Roth, & Goode, 2000
; Sekuler, Bennett, & Mamelak, 2000
) measures the ability to locate a target as a function of the eccentricity of the target, the amount of distracting elements in the display, and the presence of an added center task. Performance on the UFOV is poorly correlated with so-called “perceptual” visual attributes (contrast sensitivity, acuity, perimetry, etc.) and is instead thought to provide an index of the distribution of visual attention across the visual scene (Ball et al., 1990
; Owsley et al., 1995
). Previous results indicate that the ability to localize a peripheral target decreases with eccentricity, with distraction, and as a center task is made more difficult (Ball et al., 1988
Three different target eccentricities (10°, 20°, and 30°) were used, allowing the distribution of visual attention to be mapped as a function of eccentricity. Because the peripheral stimulus in Experiment 1 was within the range of normal video-game playing, we were unable to assess the generality of the learning across space. In the UFOV paradigm, we can test the effect of action video-game experience within, at the border of, and beyond the eccentricity at which games are typically played (our players generally reported a viewing angle of 7.5°–10° from the center of the screen). If the effect of action video-game play is specific for trained parts of the visual field, there should be little to no effect of experience at 30°, whereas if action video-game play alters processing throughout the visual field, differences should be observed at all three eccentricities.
To better understand the effect of video-game playing on the allocation of attention over the visual field, we used a paradigm that included one condition without a center task and one with a center task. By contrasting performance with and without a concurrent center task, the UFOV allowed us to test whether enhanced peripheral localization performance in VGPs may be occurring at the cost of central performance. If VGPs indeed have greater attentional resources both centrally and peripherally, as suggested in Experiment 1, the detrimental effect of the center task on peripheral localization should be lesser in VGPs than in NVGPs (while maintaining equal accuracy on the central task). Alternatively, if enhanced peripheral performance in VGPs is at the cost of central attention, we may observe a larger trade-off between central and peripheral tasks in VGPs than in NVGPs.
Finally, the paradigm we used included displays with and without distractors. Participants were first asked to perform the task without distractors and then with distractors. Performance in the distractor condition is thought to reflect the same processes as in typical visual search; however, because block order was fixed, this design does not allow us to address the issue of whether there is a discriminative effect of distractor load. Thus, our paradigm is not suited to address the role of gaming on the rate of visual search.
A total of 16 right-handed men with normal or corrected vision, none of whom had participated in Experiment 1, were classified as either VGPs or NVGPs according to the same requirements as those used in Experiment 1. Of these men, 8 were classified as VGPs (mean age = 19.5, all right-handed), and the remaining 8 fell into the NVGP category (mean age = 20.1, 7 right-handed).
The apparatus consisted of a Macintosh G3 computer running a program to present stimuli and collect the data using the MATLAB computer language (The MathWorks Inc., Natick, MA) and the Psychophysical Toolbox routines (Brainard, 1997
; Pelli, 1997
). The stimuli were displayed on a 24-in. Sony GDM-FW900 driven at 160 Hz, with 800 × 600 resolution, by an MP 850 video card (Village Tronic Computer, Sarstedt, Germany).
Stimuli and Procedure
Each observer viewed the display binocularly with his head positioned in a chin rest at a test distance of 22 cm. Each trial consisted of four successive displays presented on a large monitor. The displays were similar to those used by Ball et al. (1988)
, but stimulus size and presentation time were both decreased to account for the increased ability of comparatively younger participants.
The initial display consisted of a square outline (4° × 4°) that directed fixation to the center of the screen. After 1 s, the target stimulus, a filled triangle within a circle outline (subtending 3° × 3°), appeared along with the central fixation box. The target stimulus could appear randomly at one of 24 locations on the screen. Each location was positioned on one of eight radial spokes and at one of three possible eccentricities: 10°, 20°, or 30°. Rapid presentation of the stimulus ensured that no purposeful change in fixation could be completed during the presentation. Localization difficulty was roughly equated at all eccentricities by manipulating the exact stimulus presentation duration to allow a fair comparison of the effects of gaming across eccentricities. On the basis of the results from a few pilot VGPs (none of whom took part in the subsequent experiments), the duration of the stimulus presentation was chosen to lead to about 80% correct performance in VGPs at all three eccentricities tested. To achieve this goal, we used a shorter display presentation at 10° (6.7 ms) than at 20° and 30° (13.4 ms). By preventing ceiling effects in the VGP group, this manipulation enabled us to assess the true size of the group effects at each eccentricity.
After the test stimulus, a mask screen appeared for 750 ms. The mask screen, designed to eliminate afterimages as a possible source of information, consisted of randomly spaced vertical and horizontal lines of variable thickness and luminance, circles and squares of random sizes, and thick lines (luminance equal to that of the stimulus) that completely covered each possible stimulus location. The location, size, and contrast of the mask items were randomized for every trial to prevent the creation of potentially confounding consistent local elements. Finally, a response screen consisting of a radial pattern (eight evenly spaced spokes: four cardinal directions as well as four diagonals) appeared to direct the response. Each spoke was labeled in a one-to-one stimulus–response mapping with the keyboard number pad (i.e., the Number 8 spoke was straight up from center, the Number 4 spoke was straight left) to best facilitate participant response.
Participants were allowed to respond at any time after the presentation of the stimulus by pressing the number on the keyboard number pad corresponding to the radial spoke they believed the stimulus had appeared on. Pilot data from Ball et al. (1988)
indicated that when participants could accurately determine the radial location of the stimulus, they also knew the target’s eccentricity more than 90% of the time. Therefore, participants were not required to indicate the eccentricity of the target. Although most participants responded during the mask presentation time, if a participant had not yet responded, the spoke pattern remained visible until he made a selection. Participants were made aware that accuracy rather than speed of response was critical and that no penalty was assessed for slow responses. After participant response, feedback was given, and the participant pressed the middle key on the number pad (the number 5, which was not associated with a spoke) to initiate a new trial.
Two main levels of distraction were tested. Under the no-distractors condition (0-distractor block), the stimulus appeared alone on the screen. In the distractors-present condition, two sublevels of distraction were tested. In one (23-distractor block), distractors were present in the 23 potential target positions not occupied by the target (on the eight spokes and at all three possible eccentricities). The distractors consisted of open squares of the same luminance as the stimulus and subtending 4° × 4°. In the other (47-distractor block), the distractors occupied all of the same locations as in the half-distraction condition as well as the areas between, thus filling a 60° diameter circle with distractors. Each participant underwent 120 trials (eight spokes × three eccentricities × five repetitions of each) for each of the three distraction blocks (0, 23, and 47). The blocks were always tested in a fixed order: 0 distractors, followed by 23 distractors, and then 47 distractors. It should be noted again that for the purposes of statistics and discussion, because performance differences have not been observed between the 23- and 47-distractor block either by our own lab or others (Ball et al., 1988
), the data from the 23- and 47-distractor blocks were collapsed into the distractors-present group. This resulted in twice as many trials in the distractors-present group than in the no-distractors group. Considering also that distractor order was not counterbalanced, we chose to perform separate analyses for no-distractors and distractors-present conditions.
In a different set of blocks, one for each block of distractors (0, 23, and 47), participants performed the same peripheral localization task but also performed a center-shape discrimination task as well. The central stimulus was either an isosceles triangle or a diamond. In these blocks, participants were asked to determine which of the two shapes (triangle or diamond) was presented centrally (within the center fixation box) by pressing the correspondingly labeled key on the keyboard. Participants then indicated the spoke upon which the peripheral target fell on the keypad (in the same manner as previously described).
The experiment therefore consisted of six blocks: 0-, 23-, and 47-distractor blocks each with and without a simultaneous central task. The level of center task was counterbalanced as to which was given first, but again, the distractor conditions were always run in the order 0, 23, and 47.
To summarize, four main factors were manipulated: the amount of video-game experience of each participant (two levels: VGP vs. NVGP), the eccentricity of the target (three levels: 10°, 20°, or 30°), the amount of distraction (two levels: no distractors vs. distractors present), and the center task (two levels: no center task vs. center task present).
Because the design of the experiment did not counterbalance between distractor blocks (and thus distractor condition is confounded with task experience), peripheral localization accuracy was analyzed in two separate 2 × 3 × 2 ANOVAs, one for the no-distractors condition and one for the distractors-present condition, with video-game experience (VGP vs. NVGP), eccentricity (10°, 20°, or 30°) and center task (no center task vs. center task present) as factors. The peripheral localization data for the center task present conditions were filtered prior to analysis by removing any trials in which the center shape was incorrectly identified.
It should be noted that because several of the cell means for the NVGPs approached floor (and thus may have deviated from normality), we also performed the same ANOVAs on arcsin-transformed data. In no cases did a significant p value in the untransformed analyses become nonsignificant using the arcsin transform or vice versa, and thus for ease of interpretation, only the analyses on untransformed accuracy are presented.
Peripheral Localization Accuracy No-distractors condition
First, although we tried to match performance across eccentricities, a main effect of eccentricity, F(2, 28) = 4.7, p < .05, was still observed. Unlike previous UFOV studies, however, where the main effect of eccentricity represented decreasing accuracy with increasing eccentricity, the main effect of eccentricity here represents a failure to equalize the difficulty of each eccentricity by altering the presentation times. By using different presentation times (7 ms for 10° and 13 ms for 20° and 30°) we had hoped to achieve relatively stable performance across eccentricities. However, whereas 10° and 30° did have similar performance with these timings, performance at 20° was slightly better than both. Second, a main effect of center task, F(1, 14) = 5.2, p < .05, was observed, with participants making more peripheral localization errors when the center task was present. Finally, as predicted by our hypothesis, a main effect of video-game experience was observed (VGP: 84.3% ± 2.5; NVGP: 31.8% ± 3.6), F(1, 14) = 44.4, p < .001 (), as the VGP group outperformed the NVGP group by a large margin. No other effects reached significance.
Figure 3 Experiment 2: Accuracy of target localization as a function of eccentricity for gamers (VGPs) and nongamers (NVGPs). VGPs localize a peripheral target far more accurately than NVGPs at each eccentricity (x-axis), both without (A) and with (B) distractors (more ...) Distractors-present condition
As in the no-distractors condition, a main effect of eccentricity, F(2, 28) = 6.5, p < .01, was observed. The main effect of center task did not reach significance, F(1, 14) = 3.8, p = .07, but was in the same general direction as in the previous analysis. Again, as predicted, a large main effect of video-game experience was observed (VGP: 73.6% ± 3.0; NVGP: 30.0% ± 3.1), F(1, 14) = 37.5, p < .001 (), indicating superior localization performance by the VGPs. Finally, a Video-Game Experience × Eccentricity × Center Task interaction, F(2, 28) = 4.5, p = .02, was observed and appears to be rooted in the fact that the VGPs performed disproportionately well in the center task condition at 10° of eccentricity (fastest presentation time).
Center Identification Task Performance
The previous analyses included only trials in which the center shape identification was correct. However, to conclusively demonstrate that any differences observed in peripheral localization accuracy were not related to allocation of attention to the periphery at the expense of the center task, center shape identification was analyzed in a 2 (video-game experience: VGP vs. NVGP) × 3 (eccentricity: 10°, 20°, or 30°) ANOVA collapsed across all distractor conditions.
VGPs exhibited greater accuracy than NVGPs at the center discrimination task itself (VGP: 97.2% ± 0.8; NVGP: 90.1% ± 1.1), F(1, 14) = 25.4, p < .001. A main effect of eccentricity, F(2, 28) = 15.0, p < .001, highlights the differences in presentation time. When the peripheral stimulus was presented at 10° of eccentricity, the presentation time was one screen refresh fewer than when the peripheral stimulus was at 20° or 30°. Thus, the presentation time of the center stimulus was also decreased by this amount at 10°. VGPs were able to achieve the same level of center identification performance for each eccentricity/presentation time (10°: 98.6% ± 0.41; 20°: 97.9% ± 0.6; 30°: 95.2% ± 1.5), whereas NVGPs suffered a cost at the quicker presentation time (10°: 81.1% ± 2.5; 20°: 95.2% ± 1.0; 30°: 96.0% ± 0.8), resulting in a Video-Game Experience × Eccentricity interaction, F(2, 28) = 6.3, p = .006.
Overall Effect of Center Task on Peripheral Localization
Because the results of Experiment 1 made the specific prediction that NVGPs would be more strongly affected by the addition of a concurrent center task than VGPs, the two groups were separated and the effect of center task on peripheral localization accuracy was analyzed collapsed across eccentricities and distractor levels. As predicted, only the NVGP group showed a significant decrease in performance when the center task was added (no center task: 33.8% ± 7.1; center task present: 25.3% ± 5.8), F(1, 7) = 7.0, p = .03; the VGPs showed no such decrement (no center task: 77.9% ± 5.0; center task present: 76.3% ± 3.6), F(1, 7) = 0.2, p = .65. This pattern of results supports the conclusion that VGPs have more attentional resources available than NVGPs.
VGPs display enhanced target localization abilities under all conditions tested. VGP performance is superior to that of NVGPs at all eccentricities, with and without the addition of distractors and with or without a concurrent center task. Together, these findings support the results of Experiment 1 and demonstrate an enhancement in spatial attention in VGPs not only at peripheral but also at central locations.
VGPs more accurately localize the target at all three eccentricities (10°, 20°, and 30°), demonstrating that video-game experience enhances visual processing across a large portion of the visual field. In particular, the superior performance of VGPs at 30° suggests that the effects of video-game play generalize to untrained locations, as this eccentricity is beyond the eccentricity at which most gamers play.
VGPs also show a clear advantage in localization with or without the presence of distracting objects. The superior performance in the no-distractors condition indicates an enhancement at localizing abrupt onsets in the visual periphery. The very brief amount of time the stimulus is displayed (< 15 ms) appears sufficient to create a detectable change in the visual field that is more easily localized by the VGP population than by the NVGP population. While this condition requires the participant to locate abrupt onsets and so may draw on exogenous attention, it is also possible that improvement on this condition could be due to more perceptual factors. The advantage in the distractors-present blocks indicates that video-game experience increases the ability to select targets among distractors. Therefore, although the results of Experiment 1 could have been attributed to an increase in distractibility in VGPs, the findings of Experiment 2 conclusively demonstrate not only that more resources are available to VGPs but also that this enhanced attention can act to increase target selection. This is consistent with previous reports that have found a positive relationship between increased attention and enhanced visual selection (Carrasco & Yeshurun, 1998
; Eckstein, Shimozaki, & Abbey, 2002
; Palmer, 1994
Finally, when the center task is added, VGPs continue to substantially outperform the NVGPs. VGPs perform both tasks easily, and in fact, their localization performance shows no effect of the added center task. Conversely, NVGPs show a small decrease in task performance with the addition of a center task. The size of the falloff is consistent with previous work on the UFOV paradigm, namely, relatively modest decreases in peripheral localization performance with the addition of a center discrimination task in younger observers, with substantially larger effects being seen in the elderly (Ball et al., 1988
Of importance, VGPs outperform NVGPs on the center task itself, suggesting that no trade-off of attentional distribution is involved (although we note that it could be the case that the central task was simply easier for the VGPs). Essentially, VGPs can perform both tasks with near perfect accuracy; this suggests that the load of these two tasks combined is below their capacity limit for dual-task performance, whereas NVGPs show lessened performance at both tasks, suggesting that their capacity limit is substantially lower. This mirrors the predictions given by the results of Experiment 1 in which NVGPs were seen to have fewer attentional resources than VGPs, both peripherally and centrally.
Whereas our hypothesis predicts that extensive video-game playing leads to these enhanced skills, it could also be the case that VGPs have inherently better visual skills and/or were somehow genetically endowed with greater attentional abilities. To demonstrate a causative role of action video-game play in these effects, we trained a group of NVGPs on an action video game in Experiment 3. If the effects are due to action video-game experience, similar enhancements in localization performance should be observed following training.