内存发展: 展示如何反复质疑导致虚假记忆

Both children and adults can experience false memories, which are either memories of events that never happened, or real memories that have been altered by subsequent experiences.

Compared to adults, children are more susceptible to forming false memories. Often, such memories are harmless cases of children recalling events and experiences that never actually occurred—like going to the hospital the day their sibling was born when they actually spent the day with their grandparents.

In addition, when children remember, it can be challenging for them to separate real details and events from those that they imagined or only heard about. As a result, children are less adept than adults at judging the accuracy of their memories.

As the work of psychologist Stephen Ceci has revealed, one of the most worrisome aspects of false memories is that they can be easily created in children, for example by repeatedly asking them a question or telling them a story.

Using the techniques described by Ceci and colleagues, this video demonstrates how to design, collect, and interpret data for an experiment investigating false memories in children, as well as how to apply this method to explore the complex relationship between memory, imagination, and age.

In this experiment, 5- and 6-year-olds are told about different events involving them, and asked to remember whether they experienced these scenarios.

The scenarios consist of three types: true, check, and test events. True events are those that children were actually involved in—like having gone to the fair and winning an enormous stuffed animal—that a researcher identifies by interviewing the children’s parents or guardians beforehand.

In this case, the dependent variable is the average percentage of children that assented, or claimed to have actually experienced, true events. These events are also used to evaluate the general accuracy of children’s memory.

The second type, check events, are fantastical scenarios a researcher creates that children did not experience, for example, having played a board game with a talking dog by a roaring fire.

As these events couldn’t have happened, they ensure that children don’t get into the habit of automatically answering “Yes” to every question, and also evaluate memory accuracy.

The final type of events—test events—are the trickiest, and consist of plausible scenarios that children did not experience, such as going to see a doctor after stepping on broken glass.

The percentage of children who claimed to have experienced test events serves as the dependent variable.

Over a 5-week period, children are repeatedly asked about the same set of scenarios, which includes true, check, and test events.

Based on the previous work by Ceci and colleagues, it is expected that the percentage of children assenting to test events will increase over questioning sessions, indicating that in some children these scenarios form false memories.

To prepare for the experiment, confer with every child’s parents to identify events that they have and haven’t experienced over the last year.

Using this information, design a collection of 10 individualized vignettes on index cards for each child. Ensure that each set includes five true, three check, and two test events.

To begin the study, greet the child and introduce them to the task they will be performing. Emphasize that some of the events they will be told about didn’t actually happen.

Sit nearby while holding index cards on which events are printed.

Have the child select a card at random, and read to them what’s written on it. Afterwards, ask the child whether the event happened.

Continue until all the cards have been read, and transcribe the child’s responses. Repeat this procedure five times over a period of five weeks.

For each of these five sessions, code the child’s “yes” responses separately for true events and test events.

To analyze the data, calculate the average percentage of children who claimed to have experienced both true and test events across sessions 1, 3, and 5.

Perform an analysis of variance to determine if there are differences between the two types of events presented to children in these three sessions.

Notice the rate at which children claim to have experienced realistic test events increased over time, indicating that many of them come to believe these events actually happened—forming false memories.

Now that you know how repeated questioning can be used to investigate false memories in children, let’s look at how psychologists are studying the plasticity of memory in other contexts.

One application of this work evaluates whether repeated questioning by authority figures—such as law enforcement officials—during interviews can result in children forming false memories.

As this can have serious legal ramifications, many psychologists are looking to identify and develop questioning strategies that encourage children to accurately report what they know about an event without influencing their memory of it.

Similarly, psychologists are trying to understand how children can mistake something they’ve heard, imagined, or thought about for something that they’ve actually experienced.

This may be due to the fact that each time a memory—like a specific birthday party—is recalled, there are opportunities for details to be added to or subtracted from it—like who was there and what food was served. Thus, remembering is more like construction than recollection.

As a result, unlike photographs, over time memories can become increasingly imperfect representations of a life event.

Finally, some researchers use techniques—like functional MRI—that can identify metabolically active tissues to compare areas of the brain involved in the formation and retrieval of false and true memories.

Although individuals experience both true and false memories in much the same way, it is possible that these imaging techniques can identify structures in the brain—like the hippocampus—that may help differentiate between these types of memories.

You’ve just watched JoVE’s video on the development of false memories in children. By now, you should understand how repeated questioning can lead to false memories in children, and know how to collect and interpret data revealing children’s tendencies to form false memories. You should also have an idea of what makes children particularly susceptible to false memories.

Thanks for watching!