Old Interests and New Demands The Normative Logic of Experimental Design What Happens When All Other Things Are Not Equal? Obtaining Comparable Groups Equivalence of Treatment for Different Groups Limitations of Simple Descriptions of Group Differences Relating Group Differences to Underlying Causes Comparing Tasks and Groups Comparing Patterns of Performance The Group by Tack Interaction Approach Training Studies Cautionary Notes Model-based Approaches Qualitative information-processing Models Computer Simulation Models Mathematical Models Functional Measurement Advantages of Model-based Research Strategies Cautionary Notes From Laboratory to Life Comparing Laboratory and Real-Life Tacks Training Cognitive Processes Training Tacks of Practical Importance Value Judgments in Cognitive Research On the Reference of Basic Research Appendix. Statistical Issues in Comparative Research Attempts to Control for Pre-existing Group Differences Interpreting Group by Task Interactions References Notes Index