The effects of conversing on the phone while driving are not simple, static, or uniform. This is true for different driving conditions, different phone tasks, different driving tasks, and different people. Despite the complexity of the results, the following general conclusions can be made regarding the driving conditions and tasks examined in this study:

• There is a learning process that occurs for both the driving task and the distraction task. Over the course of five sessions there was an improvement in the performance of most of the driving measures and on the math distraction task. In parallel, the subjectively evaluated workload decreased in a fairly monotonic manner.
  
  
• Performance, in general, is poorest for the older drivers, and better for the two younger groups of drivers, which generally do not differ from each other.
  
  
• Performance on the driving task is significantly affected by the required speed, being generally poorer when required to drive at 65 mph than when required to drive at 50 mph or follow another vehicle (also at speeds less than 65 mph).
  
  
• Of the two phone distracting tasks used, the math operation is a much more difficult task, as reflected in the poorer performance on the driving measures.
  
  
• An emotionally-involving conversation is much less disruptive to driving than a math operation, and in the case of many driving measures, it appears to be non-disruptive at all (relative to the no distraction condition).
  
  
• The significant interaction of the above conditions shows that the effects of the distracting task on driving are greatest when the distracting task is difficult (math operations), the driving demands are high (65 mph), the driver has no experience in performing the dual tasks (Day 1), and the drivers are older (60-71 years old).
  
  
• Consequently, in accordance with the main hypothesis of this study, where learning is observed, practice diminishes or completely eliminates the differences in the performance on the driving task, between the no-distraction condition and the two phone distraction conditions.