Great public speakers know that the message is key. But scientists are discovering that how you structure your slide may also be important to your success.

Michael Alley has investigated an alternative to the default PowerPoint slide layout, which he terms the "assertion-evidence design."

This approach employs succinct sentence headlines (sentences that make an assertion) at the top of the slide.

Under it, in the main section of the slide, there would appear a visual representation of evidence, such as a picture or a graph.

In multiple experiments, Alley has found that students viewing presentations following this design were better able to recall the main assertion of slides than were those students viewing presentations employing phrase headlines and bulleted text.

An example of a phrase headline would be:

Product safety

This phrase that contains no information of value and no point of view.

Using Alley's "assertion-evidence design," the headline might read:

Product safety is competitive

That is, the sentence makes an assertion, and then the viewer can glance down to review the evidence on display that supports the assertion.

McKinsey and Co., a leading consulting firm, has used this methodology for years, if not decades, as have other reputable institutions, including the Lawrence Livermore Laboratory.

Any presenter whose job is to create clarity out of complexity will benefit from using Alley's "assertion-evidence design."

While Michael Alley's experiments have demonstrated that using sentence headlines and pictures on PowerPoint slides improves knowledge transfer, other researchers have not been able to duplicate those results.

Blokzijl and Andeweg have examined the effect of various slide designs in an e-learning environment on both the students' perceptions of PowerPoint presentations and the degree to which those designs support knowledge transfer.

Interestingly, the authors found that while students have a distinct preference for slides with visual support, the text only slides resulted in higher test scores.

The authors go on to express their doubts that the results of any controlled e-learning experiments can be directly applied to live presentations due to a number of real-life complicating factors, such as the speaker's oral delivery, eye contact, and the presence of an audience.

The United States military continues to explore best practices in e-learning, including the most effective use of visual displays.

However, Blokzijl and Andeweg seem to have discovered that a talented presenter can overcome the negative effects of sub-par slide design.

The question is, can scientifically designed visual displays overcome the negative effects of a poor presenter?

I suspect not.