Season 3, Episode 3: Infantile Amnesia

[Music] Hey and welcome to another episode of the Abnormal Psychologist podcast. I'm your host, Dr. Colby Taylor. That's my baby Rowan. Scream into the background if you can hear that. He's a little fussy this morning. Anyways, I am a psychologist here in Tennessee. I'm in Memphis, Tennessee. I'm also an associate professor of psychology at Christian Brothers University. So if you've been listening to other episodes, I usually introduce myself as an assistant professor of psychology. But recently, as of yesterday, I got a promotion. So I am super happy. I would do sort of a canned applause, sound effect if I was technically savvy enough. Anyways, in today's episode, I'm going to talk about infantile amnesia. And so this sort of came about, again, you can maybe hear my young kids screaming in the background. I have a almost three-year-old named Emerson, daughter and a son named Rowan. He is nine months old. And this past weekend, I splurged and took them both to see Disney on ice. Disney on ice was in town. We got tickets, weren't the cheapest tickets. We got into the place and they sold these flashlight things. It was like a snowflake. My daughter's really into Elsa and Frozen and everything. The flashlights were $35. They were also selling snow cones there. They had like an Olaf commemorative cup thing. And the snow cones were $16. I thought, this is crazy. This is crazy expensive. My kids are both under the age of three. Are they even going to remember this? Am I just sort of a fool for wasting my money on this Disney on ice thing? Because my kids, when they're older, they're probably not going to remember this. And I was talking to my mom and she said, they brought me to Disney on ice when I was younger. And I don't remember anything about it. So it's just sort of a giant waste of time. And so that's why today I thought we would do an episode on infantile amnesia, which you'll also hear called childhood amnesia. So most people's first memory isn't before the age of about two and a half years old. And lots of people really don't remember before the age of four. In prepping for this episode, I was doing some reflection. And I think my first memory, I remember like sitting in the back of a car in a car seat. And I think I was rear facing because I remember like looking out of the back windshield at like a skyscraper that's here in Memphis. There's an interstate that goes around. It wouldn't be a skyscraper in other cities. It's probably only like 10 stories tall. But it's a taller building. And I remember that. And since I was rear facing in a car seat and it's really sort of hazy and blurry, I would think I was probably between the age of two and three. But I don't really have, you know, it's just sort of a memory maybe 20 seconds long, not super clear, and really spotty. And really my memory probably before the age of six or seven is kind of spotty. I don't have like this longitudinal chronological narrative memory like I do now where I can put things in order. It's just like there's bits and pieces here. You know, I might remember a birthday party here or I might remember a holiday there. But I don't really have like this string of of well put together memories. And that's pretty normal. Again, lots of people don't remember before the age of four and almost nobody remembers before the age of two and a half. And really our memory before the age of seven is pretty sparse. It's not as detailed as our memory for other parts of our lives. Memory is kind of a funny thing when we talk about human development in the lifespan. When older people, when people in their 60s, 70s and 80s are interviewed about their memory, a lot of times they have what's called a memory bump. It's sort of a bump effect where they have pretty good memories for their teenage years and their their their 20s. Not as good of memories for like mid life, 30s, 40s and 50s. I mean, their memory is still a lot better than our memories for before the age of seven. But it's interesting that we tend to remember sort of our adolescent years, early adulthood years in more detail when we're older. Then maybe like the doldrums are our 30s and 40s. It's called like the memory bump effect. These are fascinating topics. It's a really interesting topic because it can be so quirky. We have different types of amnesia like retrograde amnesia and interrograde amnesia. They can exhibit all sorts of sort of quirky patterns. We have quirky patterns with dementia and Alzheimer's. We have some people that have a genetic memory. A genetic memory would be like perfect total recall. I think in pop culture, right, we talk about photographic memory. This memory is so fascinating. The other day, I'm recording this episode on St. Patrick's Day. It's March 17th. The other day was Pi Day, 3.14, right? March 14th. One of my colleagues, Dr. Rod Vogel, his specialty is memory. He actually worked with, I think at the time, the person that could remember out had the Guinness Book of World Records for remembering the most decimal digits of Pi. He did a TV interview with this person and studied this person. Dr. Vogel is one of my mentors at Christian Brothers University. I just think it's so fascinating. Memory basically, right? I'm not a memory expert. Dr. Vogel would be a memory expert. I am not, but again, I'm sort of a memory fan because of its quirkiness, a memory fan that's unso awkward, right? I've read some books on memory. I've tried to increase my own pneumonic strategies through the method of low-chi. That sort of thing. You can Google that if you're super interested. Or maybe I could even do a podcast on the method of low-chi in prepping for like jeopardy and for grad school exams and stuff. I try to do different memory strategies, different pneumonic strategies. But memory is broadly divided into two parts. We have declarative memory, which you'll also hear called explicit memory, and this is conscious memory. We have implicit memory, which is largely unconscious. One of the quirks with the mentor Alzheimer's, you might have people that procedurally can remember certain things. Like remember how to button their shirts or remember how to play a beautiful tune on the piano. But their memory for who their son or daughter is or where they were born might be profoundly affected. We have declarative memory, which is also called explicit memory, on the one hand, and then on the other hand, we have implicit memory. If we're sort of doing a flow chart down from declarative memory or explicit memory, that's divided into two parts. We have semantic memory, which is sort of our memory for facts. In prepping for jeopardy, I had to work on my semantic memory. Vocabulary would be semantic memory. A lot of our school smarts, book smarts, that sort of thing we would consider semantic memory. Then on the other hand, with declarative memory or explicit memory, we have episodic memory. An episodic memory is our memory for events. A lot of times when we're talking about our first memory, whether it's a birthday party or a holiday or whatever it is, a traumatic event maybe, that would be episodic memory. Really we can broadly put semantic and episodic memory together into a type of memory called autobiographical memory. Autobiographical memory we think is a combination of semantic and episodic memory. Probably more heavy on the episodic memory, but semantic memory is definitely involved. Autobiographical memory is sort of how we piece together life events into a narrative. Certain people have better autobiographical memories than others. This has been implicated in psychopathology. We think having a poorer autobiographical memory might play into major depressive disorder. We think maybe having really rich autobiographical memory might play into obsessive compulsive disorder. There's so much that we don't know about autobiographical memory. Again, there's so much that we don't know about memory in general. That's why I think it's such a fascinating topic. Memory isn't necessarily static. Carol Peterson wrote an article in memory in 2021, so one year ago. I think oftentimes we think about memory as being sort of like a thing. A thing that you can sort of like pull out of a bank. I think about the movie Inside Out, which sadly I didn't see for the first time until I think last year. The movie Inside Out is great. It's psychologically relevant. It's entertaining. I think I was more entertained as an adult than my two kids. But memory is not necessarily just like a thing that you can pull out of a bank. They pull out those balls and chord memories or whatever in Inside Out. Memory is really more of a process. It's a process that varies because we're doing retrieval and we're doing encoding. We're doing all sorts of different things. Memory is more of a verb than a noun, if that makes sense. That we can't remember early in life. This concept of infantile amnesia or childhood amnesia has been known in psychology for over a hundred years, although we still don't know exactly why it occurs. We'll talk about some theories as to why it occurs in a second. Freud had a theory about early childhood amnesia. He thought that we forget our early childhood events because childhood is full of traumatic experiences and really traumatic inappropriate sexual experiences, sexual, who would have thought with Freud? And there's different hypotheses as to why this childhood memory loss occurs. One is the language hypothesis. So kids really don't use phrase speech, you know, stringing several words together into like a coherent narrative or sentence or phrase or clause or whatever, until they're a couple years old. And if we don't really have the words to put things into a narrative and we think that a lot of memory is narrative-based, how do we remember it? How do we recall it? So maybe the fact that we can't remember before the age of two and a half is due to the fact that our language hasn't really developed before the age of two and a half. And there's still a lot of people that have, that sort of adhered to this hypothesis. It was very popular in the 80s and 90s and early 2000s, but that's the language hypothesis of early childhood amnesia. Another hypothesis is sort of the developmental hypothesis. There's different ways that this developmental hypothesis might work. But it's essentially our brain and specifically our hippocampus is not fully developed. And this can lead to some sort of losses or lapses in memory due to our neuroanatomy. And when we talk about memory, we talk about the hippocampus. And really we have two. Hippocampus means seahorse because it was thought to be seahorse-shaped. And really when you get into sort of Greek mythology, the seahorses of Greek mythology looked a lot more like real horses, with sort of like fish fins, then sort of the animal seahorse that we have now. I guess we've always had the animal seahorse. But seahorse how you would think about it, you know, with the little quirky, I don't even know how you describe a seahorse. Freaky creature, right? So we have hippocampal memory. And again, we, a lot of times like undergraduates think about the hippocampus is only having one of them, or then MIG-DELAS only having one of them. And because our brain exhibits bilateral symmetry, right? Largely exhibits bilateral symmetry. There's a few exceptions, the pineal gland being one of them. If you look at a picture of a brain, or if you look at a 3D model of a brain, right? It's split down the middle. And we call that the inter-hymisphoric fissure, or the great longitudinal fissure. There's a lot of different names for sort of that weird middle fold in the brain. The great longitudinal fissure, the longitudinal fissure, the inter-hymisphoric fissure. Anyways, and so like on one side we have a hippocampus, which is deep in our temporal lobe, right? We have several lobes in our brain, frontal, occipital, parietal, and temporal. So we don't just have several. We have four lobes of our brain. Our hippocampus would be in your temporal lobe. But again, you have two of them. You have one on your right side, one on your left side. Just like with the migdala, you have one on your right side, one on your left side. So technically we have hippocampi, but the degree to which the right side or left side is involved, is based a lot on brain lateralization, which could be the topic of another podcast. Anyways, I'm digressing big time. We do know that people under the age of two have higher rates of forgetting, which sort of plays into this developmental hypothesis. They don't keep things in memory for nearly as long as adults. Piaget, a jumpiaget, the famous developmentalist, thought that sometime in sort of the pre-operational stage, and was actually just lecturing on Piaget last week, remember Piaget has the sensory motor stage, the pre-operational stage, the concrete operational stage, the formal operational stage. This pre-operational stage is from like two to seven years. And he thought that our memory didn't really develop until sometime into our pre-operational stage, at least memory in the richness that we think about memory. And Piaget is really interesting as far as memory goes, and he was interested in memory because he had this sort of vague memory as a teenager back to when he was two. So when he, I think it was like 15, 16 years old, he thought that he remembered that somebody tried to kidnap him on the street when he was two years old. And he had a nanny at the time, and the nanny fought the kidnappers off. But nobody else recalled this event, so it seems to have been a false memory. So with this developmental hypothesis, it's not due to poor language development. It's just due to sort of hippocampal immaturity. And we have evidence of this in the animal world too. So animals don't have language, or at least anything akin to human language, yet they seem to have higher rates of forgetting sort of in their infancy, just like humans do. So this would tend to add evidence to a developmental hypothesis and not necessarily a language hypothesis. We also have a retrieval hypothesis. So maybe we're able to encode, we're able to lay down these memories perfectly fine. But that when we get older, there's some sort of obstacle that's not allowing us to sort of get that deposit out of the bank. So again, thinking about memory sort of like the inside out way. Something's blocking us from getting this ball of memories out. And maybe in a psychoanalytic sense that could be some sort of trauma. And we've repressed them like memory repression or something like that. We don't have as good of evidence for that retrieval hypothesis. That where I would, those memories are there somewhere, they're just sort of inaccessible. It's like being on a computer hard drive. It's a file that you've saved that you can't pull back up. Now to say that infants or children, young children, don't have memory would be very incorrect. In fact, the more we learn about early childhood memory, the more we think that we've underestimated over the years how much little kids can remember, how much babies can remember. We have evidence that babies have very good physiological memory. So as far as physiological memory goes, we know that babies with like heel sticks, babies that have to have repeated heel sticks, have to have blood drawn from their heels. We'll start to wince or we'll start to pull away after several heel sticks. So they definitely remember that sort of experience. So with physiological memory, we have all sorts of examples in very young kids, very young infants. That they sort of remember and experience and shy away, especially from like very painful experiences. We also know that kids have young kids have really good maybe effective memory, effective memory is memory for emotions. So they might be more likely, or be more likely to be drawn back to experiences that were happy, that were pleasurable. We think about thorn dikes law of effect, you're more likely to do things over again that are pleasurable and you're less likely to do things over again that are uncomfortable. And even young babies sort of exhibit that. We think about effective memory too, maybe babies have really good memory for their mothers. We know that babies fresh out the womb recognize their mother's scent. We know that babies in utero are able to sort of remember or at least more attracted to. There's been studies where mothers while pregnant have read the cat and hat doctor ceases the cat and the hat over and over and over again repetitively. And then once the baby is born, that the baby is more drawn to the cat and the hat than other sort of childhood stories. So there's definitely some sort of memory that's there, but that autobiographical memory that ability to sort of put into a clear and cohesive narrative events in your life. That's probably not as rich an infant. But again, we're probably underestimating the memory capabilities of really young kids. If you've studied memory at all, you might have come across different case studies of memory. And usually case studies and psychology and especially case studies of memory are really big with using sort of alphabetic pseudonyms. So you might be familiar with the case of HM. HM was if you've studied amnesia, he had an enterograde and retrograde amnesia. And it's talked about in a lot of gen site courses and a lot of memory courses. So HM, we have the case of S. The case of S. The S was a pseudonym for Solomon Cherishewski. Solomon's Cherishewski or S was studied by Alexander Luria. Alexander Luria is known as the father of neuropsychology. So you'll encounter him a lot if you're studying neuropsychology or if you're studying memory. So you'll encounter him a lot of S. Luria's paper was called the mind of a nimonist. It's really hard to say nimonist, the mind of a nimonist with that M in that weird funky M in silent in beginning. And that comes from Greek mythology. Nymosine, Nymosine, M-N-E-M-O-S-Y-N-E. I can spell it, but I don't know if I can say it. Nymosine, Nymosine. the mother of the nine muses and the reason that we see that that M in E, M sort of prefix and a lot of, maybe not even a prefix, but that combination of letters when we're talking about memory is that she was the goddess of memory in ancient Greece, Nymocene, Nymosine. So the case of S is really fascinating because he had a great memory, but he also used retrieval strategies, whereas there's other people that have H-SAM, which is an acronym, H-S-A-M, and that stands for hyperthymesia. Hyperthymesia is having a highly superior autobiographical memory. And unlike the case of S, people with H-SAM don't use deliberate memory strategies. So they're not using these elaborate, pneumonic strategies like the method of locai to recall events. It's not deliberate, they don't do this purposefully, but they have really, really good memory for events in their lives. One case, the case of AJ, so again, back to the sort of alphabet soup. AJ was a pseudonym for Jill Price. She had almost a perfect memory of every day of her life since the age of 14. So even folks with this hyperthymesia, this H-SAM, don't tend to have very good, very vivid, or really any memory before the age of two and a half. So even if you have perfect autobiographical memory, it's usually perfect autobiographical memory from some point in middle or later childhood. We also have evidence going back to the original question that I had about, was it worth it for me to buy these expensive tickets to Disney on ice and buy these expensive toys and snow cones or whatever? We do have evidence that early emotional experiences, well, they might not be recalled through autobiographical memory. They are important to later development. To prove this, we don't really have to look any further than traumatic events and infancy in early childhood. We know that experiencing a traumatic event, even at a super young age, can have profound and long lasting impacts on that person's life. You can be diagnosed with PTSD at a very young age. I don't think it's generally, it's sort of an unwritten rule, not to diagnose PTSD before the age of nine months, but kids can be diagnosed in toddlerhood with PTSD. And so even though you might not remember super vividly, the event that happened to you, it can still have a long lasting impact on your life. And so if negative events, traumatic events can have a long lasting impact on your life, there's no reason to think that positive events and hopefully going to Disney on ice was a positive event. Even though when Emerson and Rowan are 20 or 30 years old, they might not be able to remember in as much detail or any detail the experience of Disney on ice, so it's still probably a good thing to provide your child with rich emotional, positive emotional experiences, even if they don't remember it later in life. Okay, so that's infantile amnesia, early childhood amnesia. If you have any questions about it, any other episode requests, you can email me at C-T-A-Y-L-O-O-4-1 at cbu.edu. Just put the subject line mail bag. And I'll be happy to answer any questions, do episode requests. You can tell me if you like the podcast, you don't like the podcast, whatever. I'm just always happy to receive emails. And speaking of emails, I do have an episode request and this was from earlier last season, I wasn't able to get to it. But the mail bag is from Haley and Haley says, I wanted to start off by saying that your podcast is absolutely wonderful. I actually recently found your podcast and found it so interesting and entertaining that I within a week and a half have finished every episode. I'm wondering if you were able to do an episode on regression. I have myself experienced a lot of it when I was extremely emotionally distressed. I typically go into cycles of extreme anger, to sadness, then regression, where are you talking to act more childlike? This includes laughing and childish behaviors, like I'm more around the age of four and five when I'm actually the age of 18. I want to thank you so much for these episodes. They've helped me to open up a world of psychology and increased my want to complete my degree in psychology. So this is a great mail bag request. I'm happy to talk about regression. Again, I'm teaching a human development course as a semester. I can tie in some of my teaching experience to this next episode. Thinking ahead to future episodes, the DSM-5 is dropping a new text revision within the next couple of weeks. And so maybe the third second episode out from here, so I'll do regression the next episode. And then maybe I'll get into some of the revisions in that text revision of the DSM-5. So until then, send me some email, [email protected]. Hope you're enjoying the beginning of spring. If you're listening to this on St. Patrick's Day, I'm happy St. Patrick's Day. And until the next time, take care and stay well.