False memories possible in William Tyrrell mystery
A memory expert has told the inquest into missing boy William Tyrrell that two crucial pieces of eyewitness testimony in the case could be false memories.
William was wearing a Spider-Man suit and pretending to be a tiger when he vanished from his foster grandmother's home on Benaroon Drive in the quiet northern NSW town of Kendall on September 12, 2014.
An inquest has been under way since March 2019 before deputy state coroner Harriet Grahame, tasked with unravelling the mystery of what happened to the missing three-year-old.
It is expected to finish this week, but the police investigation is still under way.
"Have you given up?" counsel assisting Gerard Craddock asked lead investigator detective Chief Inspector David Laidlaw on Wednesday.
"No," he replied. "We never will."
Dr Helen Paterson, a lecturer in forensic psychology at the University of Sydney, told the inquest on Wednesday "our memories are not perfect … we don't remember things like video cameras".
"Many people think memories are reproductions of what we saw," she said. "But every time we recall an event we reconstruct it."
Dr Paterson examined testimony from William's foster mother that two unfamiliar sedans had been parked on the quiet, rural street the morning William disappeared.
She initially told police she had not seen any suspicious cars but remembered two days after the fact, insisting to police the picture was "burnt into my brain".
It has not been corroborated by other witnesses.
"I can't say if it's a genuine memory or a false memory. I can say that it is possibly a false memory," Dr Paterson said on Wednesday.
She offered several possibilities: The foster mother could have genuinely seen the cars that morning, she could have seen them on a different day, or a leading question or photograph could have planted the notion in her mind, generating a false memory.
The foster carer said she remembered looking out the window around 7.30am and thinking it was unusual to have cars parked on the street and so close together.
The memory of this thought could also be from another day, Dr Paterson said.
Dr Paterson said confidence was not always a good indicator of accuracy, and sometimes people who were very sure of a memory and often repeated it to others could have a "confidence inflation" effect over time.
She said this effect appeared to be present in the testimony of Kendall man Ron Chapman, who said he saw two cars drive past his house erratically that morning in 2014.
The first car was driven by a woman and William Tyrrell was standing unrestrained in the back seat, dressed in his Spider-Man suit, Mr Chapman told the inquest last year.
"Originally, he wasn't very confident at all," Dr Paterson said.
"He wasn't sure if it was a dream or whatever and he became more confident over time, that he had seen William Tyrrell in the vehicle that went past."
Mr Chapman had relied on "script" memory - or what typically happens - in his interview, she said, noting he had misremembered his relatives had been in town and it had not been an ordinary day.
Dr Paterson assumed for her report that neither Mr Chapman nor the foster mother were lying, and each was trying their best to give an honest account.
Broadly speaking, humans were very bad at telling if people were lying, particularly based on their demeanour, Dr Paterson said.
She told the court it was possible to experience "inattentional blindness" in which you do not notice and cannot recall something that happens right in front of you.
This has been measured by experiments, she said, the most famous involving a person who is asked to watch a video and focus on three people in white shirts passing a ball to each other.
A person focused on the task tended to miss a "very obvious" person in a gorilla suit who walks into the middle of the game and beats his chest, she said.
Insp Laidlaw told the inquest there were police working full time on the Tyrrell investigation to this day.
He said when he took over the investigation from former detective Gary Jubelin in early 2019 he chose not to do a handover.
"My view at that stage was that I was going to get more knowledge of the investigation from all those who worked on it, not just the person," he said.
"It's always been with me, 'It's we rather than me'."
Jubelin was stood down from the investigation and later resigned from the police force after he was accused of illegally recording a person of interest, of which he was later convicted.
The inquest continues
Originally published as False memories possible in William mystery