Final answer:
Social loafing is the phenomenon where there is a reduction in individual effort when individuals work in a group compared to when they work alone, especially on simple tasks. On complex tasks, the effect of social loafing is reduced as individuals feel their contributions are necessary for group success.
Step-by-step explanation:
The phenomenon where individuals tend to exert less effort when working within a group compared to working alone is known as social loafing. This effect can lead to a decline in performance, especially on simpler tasks because the group's contribution is pooled and individual performance cannot be readily evaluated. This lack of accountability reduces motivation to perform well, as individual efforts are not singled out for recognition or critique. However, when tasks are complex and difficult, social loafing tends to decrease, and individuals in a student work group may feel more motivated to contribute actively, as they perceive their input is vital for the success of the group.