Observation and Memory Skills Flashcards

A bank robbery witness accurately describes the suspect's jacket colour and approximate height but later insists the suspect wore a hat — a detail absent from her initial statement but present in a news broadcast she watched the following day. Under memory research, this phenomenon is best described as:

Answer: Post-event misinformation contamination of the original memory trace

Post-event misinformation contamination (Loftus's misinformation effect) occurs when exposure to inaccurate post-event information — such as a news broadcast — overwrites or merges with the original memory trace, causing witnesses to 'remember' details they never actually encoded. The witness did not misidentify a known person (transference), nor is this primarily a weapon-focus or retrograde-inhibition issue.

Investigator Wells distinguishes between 'estimator variables' and 'system variables' in eyewitness research. Which of the following correctly identifies an estimator variable that an investigator CANNOT control?

Answer: The lighting conditions present at the scene during the offence

Estimator variables are factors the criminal justice system cannot control but can only estimate their impact — such as lighting, distance, stress level, or duration of the event. System variables (lineup size, administrator knowledge, pre-lineup instructions) are within investigator control and can be manipulated to reduce error. Lighting at the original crime scene is an estimator variable because it was fixed at the time of the offence.

A witness to a violent assault demonstrates remarkably detailed memory for the attacker's knife — its blade length, handle colour, and a nick on the blade — but cannot reliably describe the attacker's face or clothing. Which memory phenomenon most precisely accounts for this pattern?

Answer: Selective encoding attributable to the weapon-focus effect

The weapon-focus effect describes the well-documented tendency for witnesses in weapon-present crimes to allocate the majority of their attentional resources toward the weapon, at the expense of encoding the perpetrator's facial and clothing features. The result is excellent memory for the weapon paired with poor memory for the suspect — exactly the pattern described. Cross-race bias affects face recognition specifically and is not triggered here; encoding specificity and Ebbinghaus decay do not explain the intra-event allocation of attention.

A detective administering a live lineup for a suspect in a series of arsons is blind to which position the suspect occupies. Partway through, the witness pauses and says, 'I'm not certain, but maybe number three?' The detective responds, 'Take your time; look carefully.' Research on administrator feedback indicates this response is:

Answer: Problematic because any post-identification response can inflate reported witness confidence

Research by Wells and Bradfield demonstrated that even neutral, non-confirmatory statements made by an administrator after a witness's tentative identification can significantly inflate the witness's later reported confidence, retrospective clarity of view, and certainty — a phenomenon called the 'post-identification feedback effect.' Because the witness has already indicated a tentative selection (number three), any response — including ostensibly neutral encouragement — constitutes post-identification feedback that contaminates the witness's self-assessment. Double-blind administration is designed to eliminate this, but the administrator's verbal response here still creates risk.

Two eyewitnesses independently observed a suspect fleeing a convenience store theft. Witness A viewed the suspect under sodium-vapour (yellow) streetlights for roughly 45 seconds from 12 metres. Witness B viewed the suspect under full-spectrum LED lighting for approximately 8 seconds from 4 metres at high emotional arousal. When assessing overall identification reliability, which factor MOST undermines Witness B's advantage in proximity?

Answer: The inverted-U relationship between arousal and memory performance (Yerkes-Dodson), which impairs encoding at extreme stress levels

The Yerkes-Dodson law describes an inverted-U relationship between arousal/stress and cognitive performance: moderate arousal optimises encoding, but high arousal (as in a highly emotional witness) degrades it. Witness B's proximity advantage is substantially undermined by high emotional arousal impairing encoding of facial details. While short duration (8 seconds) is also a concern, the question asks for the factor MOST undermining the proximity advantage — the research literature consistently identifies extreme arousal as the more powerful moderator of identification accuracy than duration alone in these conditions. Sodium-vapour light does distort colour but does not benefit feature encoding, and own-age bias is not indicated by the scenario.

During a cognitive interview, a detective asks a witness to mentally reinstate the context of a robbery and then narrate events in reverse chronological order — starting from when police arrived and working backward to entering the store. The primary investigative rationale for reverse-order recall is:

Answer: To reduce the influence of schematic expectations and generic scripts that could contaminate the witness's account

Reverse-order recall — one of the four core mnemonics of the Cognitive Interview developed by Geiselman and Fisher — works primarily by disrupting the witness's reliance on prior knowledge schemas and generic event scripts (e.g., 'what normally happens in a robbery'). When witnesses reconstruct events forward, they often fill gaps using scripted expectations rather than genuine episodic memory. Recalling in reverse makes schema-driven gap-filling cognitively costly and increases the likelihood that what is reported reflects actual encoding. Mental context reinstatement targets encoding specificity (option C), which is a separate mnemonic. Physiological arousal re-activation and interviewer confirmation bias are not the mechanism targeted by this specific technique.