Current research:

Attention remains a major area of investigation within psychology and neuroscience. Many of the major debates of James' time remain unresolved. For example, although most scientists accept that attention can be split, strong proof has remained elusive. And there is still no widely-accepted definition of attention more concrete than that given in the James quote above. This lack of progress has led many observers to speculate that attention refers to many separate processes without a common mechanism.

Areas of active investigation involve determining the source of the signals that generate attention, the effects of these signals on the tuning properties of sensory neurons, and the relationship between attention and other cognitive processes like working memory. Some speculative research has even shown that flies may be able to attend (using a brain the size of a poppy seed) in much the same way neurologically as humans do.

Human attention:

What members of a species will pay attention to is a function of their evolutionary and cultural history. In the case of humans there are problems presented by ecosystem changes resulting from human mobility and cultural artifacts. Humans no longer live in the ecosystem they evolved in, but in an ecosystem of their own creation. To take a mundane example, humans are attracted to sweet food, an adaptive trait for hunting and gathering, not so adaptive for modern nutrition.

A more substantial problem is presented by the human propensity to focus on emergency situations to the exclusion of background phenomena which may be more significant. This can be seen in what is considered news where a spectacular auto accident easily outweighs a report on particulate pollution by diesel engines although only a few may have died in the accident while thousands may suffer and die due to diesel pollution.