Refining the blank line-up procedure: How should we instruct eyewitnesses?

Presenting a blank line-up—containing only fillers—to witnesses prior to showing a real line-up might be useful for screening out those who pick from the blank line-up as unreliable witnesses. We show that the effectiveness of this procedure varies depending on instructions given to witnesses. Participants (N = 462) viewed a simulated crime and attempted to identify the perpetrator from a line-up approximately 1 week later. Rejecting a blank line-up was associated with greater identification accuracy and greater diagnosticity of suspect identifications, but only when witnesses were instructed prior to the blank line-up that they would view a series of line-ups; the procedure was ineffective for screening when witnesses were advised they would view two line-ups or received no instruction. These results highlight the importance of instructions used in the blank line-up procedure, and the need for better understanding of how to interpret choosing patterns in this paradigm.     

Growth points in research on memory and hippocampus.

We present an overview of two of our on-going projects relating processes in the hippocampus to memory. We are trying to understand why retrograde amnesia occurs after damage to the hippocampus. Our experiments establish the generality of several new retrograde amnesia phenomena that are at odds with the consensus view of the role of the hippocampus in memory. We show in many memory tasks that complete damage to the hippocampus produces retrograde amnesia that is equivalent for recent and remote memories. Retrograde amnesia affects a much wider range of memory tasks than anterograde amnesia. Normal hippocampal processes can interfere with retention of a long-term memory stored outside the hippocampus. We conclude that the hippocampus competes with nonhippocampal systems during memory encoding and retrieval. Finally, we outline a project to understand and manipulate adult hippocampal neurogenesis in order to repair damaged hippocampal circuitry to recover lost cognitive functions.