When two objects are presented within about 500 ms, identification of the first is highly accurate, while identification of the second is significantly impaired. This second-target deficit, known as the attentional blink, reveals a fundamental limitation in our ability to allocate processing resources to sequential objects. The present work examined the locus of this processing limitation using functional magnetic resonance imaging to monitor activity in primary visual cortex during an attentional blink task. The results showed that identification of an initial target leads to a reduction in cortical activation for a trailing target. This demonstrates for the first time that object identification impairs allocation of low-level perceptual resources to temporally-trailing sensory inputs.