Final answer:
Bob's teacher using exaggerated and then progressively less distinct features to teach him to distinguish between boys and girls is an example of discrimination training.
Step-by-step explanation:
When Bob's teacher used pictures with exaggerated gender features and then gradually used pictures with less exaggerated features, this is an example of discrimination training. In discrimination training, an individual learns to respond differently to various stimuli that differ in some way. The technique often starts with very distinct stimuli and then slowly moves towards stimuli that are less clearly differentiated. This approach helps the learner to recognize and respond appropriately to subtle differences between the stimuli, which is critical to understanding and categorizing nuanced information in the real world. In the context of gender, it's important to be cautious about reinforcing stereotypes, as these can contribute to gender stratification and sexism, which have been pervasive in society and educational settings.