Memory and the Reliability of the Gospels

Bart Ehrman claims psychological studies on memory challenge the reliability of the Gospels. I’ve responded in detail in the previous post. This is a summary of the main arguments for those who may not have time to read the longer post.

I’ve based my response on the debate between Bart Ehrman and Richard Bauckham. Ehrman makes two main points:

  • Memory is unreliable – the disciples are unlikely to have remembered events that happened in Jesus’ life with accuracy.
  • It is common for people to confuse events that happened with things they have imagined. So it’s difficult to tell if the Gospels contain the truth or are a product of the disciples’ imagination.

Issue 1: Ehrman on the unreliability of memory: Challenger Disaster study

Ehrman quotes a study looking at university students’ memory of the Challenger disaster. The students later responses are often confused. Many can’t even remember filling in a questionnaire at the time of the disaster. He concludes psychologists have shown we cannot trust our memories.

Ehrman is quoting a classic study by Neisser and Harsch (1992). But it can be misleading to consider an individual study in isolation. There are many studies on ‘flashbulb memories’ – memories of unexpected events with high emotion attached to them. I’ll assess how this study sits within the context of several similar studies.

The only systematic review I could find on this topic was van Giezen et al (2005). This is a little out of date but includes 18 studies on flashbulb memories like Neisser and Harsch (1992).

Study limitations

Van Giezen et al (2005) rated the quality of individual studies as ‘relatively low’. For example, the Neisser and Harsch (1992) study receives a score of 2 out of 5 for study quality. This indicates a weak set of studies.

Inconsistency

There is considerable inconsistency in findings. Van Giezen et al (2005) found reasonable accuracy in recall over time in some studies. But a decline in accuracy in others.

For example, Neisser (1996) found Californian students’ had near-perfect accuracy (96-99%) remembering an earthquake in Loma Prieta (California) 18 months later. But, Atlanta students had less accurate recall (55% accuracy) for the same earthquake. Studies after 2005 show a similar pattern.

Does the accuracy of memory differ depending on how involved you are with events?

I’m going to expand on the finding above from Neisser (1996). We’ve seen Californian students had a very accurate memory of the Loma Prieta earthquake. In contrast, students more remote to the location had a much poorer recall.

A similar study replicated these findings – this time based on the Marmara earthquake in Turkey. Er (2003) studied a bigger (665 people) and more representative (i.e. not just students) sample of people. Six months later, people who lived in Marmara had near-perfect accuracy in their memories of the earthquake. Yet people who lived in another city (Mersin) had much less accurate memory of the events.

Are these accurate memories just for 6 months or 18 months? What about memory over longer periods?

It’s very difficult to study memory over many decades, so there aren’t many studies that look into this. Berntsen and Thomsen (2005) assessed memory of the invasion and liberation of Denmark during World War II – between 63-68 years after the events. They compared people living through these events with members of the psychology faculty who were not yet alive then.

The contrast between groups was compelling:

  • Older Danes witnessing the invasion and liberation remembered these events with surprising accuracy. Most correctly recalled the weather on these days. They also remembered accurately whether these events happened on a Sunday or week day.
  • Older Danes recall was lower for more specific details. They were less accurate at recalling the actual day of the invasion and liberation. They had less accurate recall of the precise day invading Germans required households to draw their curtains. But their memory was more accurate than those who did not experience the events.
  • False memory of events was very rare for both groups.
  • Those connected to the Danish Resistance Movement had more accurate memories than those who were not connected to the Resistance Movement. Further highlighting the importance of being closely connected to events.

Issue 2: Do people often mistake events they imagined from what happened?

Ehrman quotes a study to illustrate we are susceptible to develop false memories. Based on his description, he is referring to Seamon et al (2006). 40 undergraduate students were taken on a campus tour. Half of the time, they were asked to perform familiar (e.g. check the Pepsi machine for change) or bizarre (e.g. propose marriage to a Pepsi machine) actions. The other half, they were asked to imagine performing these actions. Here is Ehrman’s summary :

“It turns out that 2 weeks later after they interview the students. When they ask students ‘do you remember doing this? Do you remember going down on one knee and proposing marriage to the Pepsi machine?’ If the student had simply imagined doing it two weeks later they remember actually doing it.’ Bart Ehrman (from around 19:00 on the video)

The extent to which the study can identify ‘false memory’ is unknown

The study quoted by Ehrman only assesses belief about memory. Brewin and Andrews (2017) argue studies of false memory need to assess ‘recollective experience’ of the events. So “the extent to which these procedures produce full autobiographical memories is unknown” p18

It was rare for participants to believe imagined events happened.

Listening to Ehrman’s summary, I was expecting to see very high rates of ‘false memory’. Yet, the data shows the opposite. On average, participants believed they had performed imagined events for 7-12% of actions. So, on average, they correctly remembered imagining events 88-93% of the time.

Ehrman’s summary does not reflect what the study found. We should be aware that we sometimes can confuse imagined actions with what happened. What the study doesn’t show is this is a common problem.

The data shows a high level of accuracy for recalling events

People were asked to recall from 72 actions/imaginations over 2 different sessions:

  • On average 78-91% correctly recalled performing a ‘bizarre’ action – this was a little lower for ‘familiar’ actions (on average 64-77%)
  • On average only 2% claimed to have performed an action that they had neither performed or imagined

Can we generalise these results to everyday or historical events?

This study is designed to confuse imagined and actual events in an inevitably artificial way. This is a limitation for many ‘laboratory’ studies of human participants. That’s not to devalue the research. But it is far from obvious if these findings generalise to how people in their real lives mix up imagined and actual events. Even if the results are valid they may reflect an overestimate of ‘false memory’.

What do similar studies find?

It’s important to compare this study with other similar studies investigating false memory. A recent systematic review identified a large number of studies testing if it was possible to create false childhood memories in adults. This is particularly interesting as we would expect to see the highest rates of false memory in these studies.

Brewin and Andrews (2017) included:

  • 16 studies on imagination inflation (where studies assess whether imagining an event can increase the belief that the event happened).
  • 15 studies on false feedback (where the impact of providing false feedback to study participants is measured).
  • 20 studies on memory implantation (where psychologists try to implant memory of participants childhoods from scratch)

Brewin and Andrews, looking at a wider range of studies, come to similar conclusions to my critique of Ehrman above:

“There are sufficient grounds to conclude that a (probably small) minority of people might develop false memories of childhood events with these characteristics and that any such memories might contain a mixture of true and false elements.” p20

“…we believe it cannot be concluded that false memories of childhood events possessing these characteristics are common, that they are easy to suggest or implant or that the majority of individuals are susceptible to them.” p20

Summary and Conclusions

In summary, we can agree with Bart Ehrman that human memory is fallible. But Ehrman’s conclusions do not provide an accurate summary of the psychological data. He cites studies that fit his narrative. But he underplays the variability of findings in similar studies. For example, he dismisses evidence showing greater accuracy in memory for those more connected to events.

We also agree with Ehrman that people sometimes mix up what they imagined with what happened. But this happens rarely both in the study he cited and in a much wider number of studies.

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