As a mobile device downloads information, it will not display the information until the whole data package is available. This delay is referred to as “buffering”. The human brain is the same. If an image requires more than three seconds to analyse and “download”, the brain will buffer, blocking all other inputs such as spoken word, until either the meaning is decoded or the observer actively aborts the process and changes input back to listening. Buffering happens in a presentation when complex graphical information is displayed.
Audience members have a finite and therefore limited working memory. If this is overwhelmed, the message fails. Cognitive Load Theory suggests three basic loads are experienced; intrinsic, extraneous and germane. The combination of these loads affects the ability to process effectively. If the load overwhelms the processing ability, there will be buffering. The information will not be effectively processed and the message will be impaired.
The intrinsic load is the essential complexity of a topic. As a presenter, your responsibility is to manage how that complex information is delivered. Inherently, that complexity cannot be reduced; advanced physiology for instance is complex. Stacking ideas with multiple cognitive leaps in a short time frame will lead to overload and buffering in the audience.
Extraneous load is the mental effort spent on decoding bad design; this is complex data slides. A forest plot followed by a data table followed by a candlestick plot followed by a regression curve followed by a histogram followed by a bar chart will overload the processing capability due to the mental challenge of changing graphical type and complexity and lead to buffering. Whilst the presenter may clearly and effortlessly understand the nature and implication of a graphs and steps having rehearsed and designed them, the audience will require to interpret and decipher the meaning and this overload will cause buffering to occur. This is avoidable and manageable.
Lastly, there is germane load, where the audience spend mental processing effort to organise and integrate the new knowledge being provided. If there is no space physically, mentally or temporally to process due either to the continuing complexity or simply volume of information being delivered, this cognitive load will overwhelm processing and lead to buffering. The meaning and value of the message will be lost.
An effective presentation must minimise this Cognitive Load. Take more time to deliver complex information, if required under the intrinsic load. Reduce the complexity of extraneous load by simplifying and standardising the nature of data display. Leave space in the presentation for germane load of processing. By reducing the risk of buffering, you are dramatically increasing the possibility of effective data transfer and communication.