Does Having Plants in the Office Improve Focus?

Doing mentally fatiguing office work may be easier if plants are in the office.

Reviewed by Jessica Schrader

Key points

• A recent study explored the impact of indoor plants on central executive functions.
• The findings suggest that plants had a restorative effect on cognitive function during a proofreading task.
• The overall results indicated that indoor plants positively impacted students' attentional capacity.

Attention restoration theory (ART) proposes that attention is split into two types: directed attention (voluntary), which has limited capacity and can be depleted by mentally taxing tasks, and undirected attention (involuntary), which does not require conscious effort. When people engage with natural environments, the complexity and patterns in these settings offer soft fascination—a gentle form of stimulation that engages undirected attention, allowing the directed attention system to rest and recover, ultimately restoring cognitive function and attention capacity.

In this randomized controlled study, 34 university students from Norway, with an average age of about 25 and of which around two-thirds were women, participated. The intervention involved placing four indoor plants in the office environment.

The study explored the impact of indoor plants on central executive functions, which are responsible for managing attention between memory and response systems. The central executive function can be thought of as a directed attention CEO, and is thought to be the aspect of attention most susceptible to mental fatigue, making it likely to benefit from restorative environments like those provided by natural elements, such as indoor plants.

The central executive function in this study was measured using the Reading Span Task (RST). Participants read out loud sentences presented on a computer screen and were asked to memorize the last word in each sentence. The task involved 96 sentences, broken down into 12 trials of four sentences followed by eight trials of six sentences. After each trial, participants wrote the last word from each sentence in numbered spaces on an answer sheet. The RST score was based on the percentage of correctly memorized words, making it a mentally exhausting task that simulates the cognitive demands of office work.

Participants completed the RST three times: first at the start of the session, then after a 15-minute proofreading task designed to induce cognitive fatigue, and finally after a five-minute break. Each RST session lasted around 10 minutes.

Preliminary analysis showed no significant effects based on gender, so this factor was excluded from further consideration. The participants in the plant group showed improved performance after the proofreading task, both in remembering the last words in sequence and in any order. However, they did not show further improvement after the short break. Meanwhile, the control group, which was not exposed to plants, showed no improvement at any stage.

The main finding of the study was that the plant group’s performance improved more significantly over time compared to the no-plant group, even though there was no difference in their absolute performance at any individual time point. This suggests that the plants had a restorative effect on cognitive function during the proofreading task, which is consistent with attention restoration theory.

No improvement was observed after the break in either group. Possibly, the presence of the plants might have enhanced the central executive function performance of the participants fully after the proofreading task, to the point at which the restorative effect was fully utilized and no further improvements were gained from taking the five-minute break. Or it could be that the break might not have been long enough to provide further cognitive restoration. Additionally, the constant presence of the experimenter might have affected the participants' ability to fully relax during the break.

Out of 16 p-values calculated in the study, four were statistically significant. All of these significant findings supported the idea that plants in the environment improved central executive function after participants engaged in a cognitively demanding task. While the fact that many tests were conducted increased the risk of false positives, the overall results of the study indicate that the indoor plants positively impacted attentional capacity in these university students.

This study summary also appears in audio format as part of the cognitive performance study of the week series on The Cognitive Performance Podcast.