Final answer:
The Atkinson-Shiffrin model of memory suggests that unattended information is weakened, not completely blocked.
Step-by-step explanation:
The model of selective attention that suggests that unattended information is weakened, rather than completely blocked, is the Atkinson-Shiffrin model of memory. According to this model, information is processed through three systems: sensory memory, short-term memory, and long-term memory. In this model, unattended information may be briefly held in sensory memory but is not transferred to short-term memory unless it receives attention. Therefore, the unattended information may be weakened or forgotten.