A new study published in the Journal of Computer Assisted Learning suggests that revealing bullet points, graphs and illustrations on a slide one piece at a time as the lecturer speaks can sharpen students’ focus and improve recall. The eye-tracking experiment used a recorded biology lecture and compared a cumulative presentation format with a traditional whole-slide exposure.
In the research, the team argues that processing spoken explanation alongside a crowded visual on a screen taxes two channels of working memory, potentially increasing cognitive load and hampering comprehension. The study sits within the cognitive theory of multimedia learning, which advocates segmenting material and guiding learners’ visual attention to reduce overload.
The researchers point to the segmenting principle, which involves breaking complex material into smaller, sequential parts, and note that prior meta-analyses have found bite-sized segments aid understanding and memory. They also emphasise the value of visual cueing and temporal contiguity—aligning where students look with what the instructor is saying at the same moment.
Coordinated cues, the study suggests, anchor attention to the relevant visuals. A 2019 eye-tracking series found that directing attention to the correct graphic element while the narrator stressed it improved both gaze and test performance.
The work builds on the cumulative presentation concept developed by first author Hikaru Ito and Hiroko Ichikawa of the Graduate School of Science and Technology at Tokyo University of Science in Chiba. In their format, slide elements are revealed one by one in sync with narration and stay on screen as new pieces are added, allowing students to see how the topic pieces fit together.
“Teachers often reveal parts of a slide as they explain them, leaving earlier parts visible. As far as we knew, no one had used eye tracking to measure how this practice guides students’ attention, so we wanted to see where students looked and whether the way we presented the slides affected what they learned,” Ichikawa told PsyPost.
A sample of 40 Japanese university students majoring in science and engineering, aged 18 to 24, were randomly assigned to the cumulative or whole-slide condition. The participants completed a 12-minute pre-test to establish baseline knowledge before watching a 20-minute recorded biology lesson on species interactions, with content across seven slides.
All participants sat about 60 centimetres from a 24-inch monitor fitted with an eye-tracking camera and were instructed to focus on the screen and not take notes. Both groups heard the same narration and saw identical content, but the cumulative group had each element appear as it was discussed and remain visible, whereas the whole-slide group saw all elements at once.
Eye movements were recorded across 32 target zones spanning text and graphics. The researchers looked at how quickly a learner’s gaze landed on a target once the corresponding topic began and how long it lingered on that zone.
Post-lesson testing occurred immediately after the video. The 12-minute post-test included multiple-choice items, graph interpretation tasks and short open-ended questions, with scores out of 20. A brief questionnaire also measured perceived difficulty, though the authors note it did not reveal clear differences between groups.
On the tests, the cumulative group outperformed the whole-slide group, averaging 17.70 out of 20 versus 16.70. The cumulative group also showed a larger gain from pre- to post-test—about 6.4 points compared with 4.2 points for the whole-slide group. The authors describe the post-test difference as a medium-sized effect (0.49), statistically significant but narrowly so.
Eye-tracking revealed sharper differences in how learners directed their attention. When the instructor began discussing a visual, cumulative-group students looked at the matching element after about one second, compared with roughly 5.75 seconds for the whole-slide group. Across the 20-minute lesson, cumulative learners spent about 442 seconds looking at the relevant visuals, versus about 326 seconds for the whole-slide group.
Total time spent looking at any part of the monitor was similar between groups—roughly 802 seconds for the cumulative group and 791 seconds for the whole-slide group—suggesting that the observed differences were not simply due to overall screen engagement. When considering the time spent on target visuals across the entire duration of each slide, including moments before the narration began, the figures were 487 seconds for whole-slide and 442 seconds for cumulative, a gap not reaching statistical significance.
The authors contend that simply looking longer at a slide does not guarantee better learning. Presenting an entire slide at once may force students to search the screen for the referenced element, potentially hindering the link between spoken explanation and visuals. Incremental reveals, they argue, can reduce that search and improve integration.
Ichikawa described the findings as lending experimental support to practices teachers often refine through experience. “That gives experimental support to something teachers have learned through experience,” she said, adding that she is curious about other small slide-design choices that might boost learning.
She also warned that the new format may not suit every learner. “Students who already know the material may be ready to move on while the teacher is still explaining, so revealing information gradually could slow them down,” she said. “I’d also like to know whether students who have the skills or the motivation to explore a graph on their own might learn more if they could see the whole graph from the start. We’d like to test those possibilities in future work.”
The study, “Cumulative Presentation Enhances Learning Outcomes by Directing Learners’ Visual Attention,” was authored by Hikaru Ito and Hiroko Ichikawa.
