Final answer:
Toddlers developing a fear of trucks and motorcycles in addition to moving cars exemplify stimulus generalization, a concept in psychology where a conditioned response to one stimulus is elicited by similar stimuli.
Step-by-step explanation:
The phenomenon where toddlers are taught to fear moving cars and also develop a fear of trucks and motorcycles illustrates stimulus generalization. This psychological process occurs during classical conditioning when a subject responds to a new, similar stimulus as if it were the original conditioned stimulus. This can be seen in the case of Little Albert, who was conditioned to fear a white rat and then generalized this fear to other similar furry objects.
In the context of cognitive development, stimulus generalization is part of how children learn to relate to the world around them. It demonstrates the breadth of their learning and the formation of schemas—or mental models—that help them understand new experiences. However, it can also result in the transfer of fears and anxieties to a broader set of stimuli, as in the case of fearing not only cars but also other moving vehicles like trucks and motorcycles.