OFFICIAL14 Why does the professor mention a study with a word list?

[00:00.00]NARRATOR: Listen to part of a lecture in a psychology class.
[00:05.42]FEMALE PROFESSOR: We've said that the term “cognition” refers to mental states like knowing and believing, and to mental processes that we use to arrive at those states. [00:16.76]So, for example, reasoning is a cognitive process.So is perception--[00:22.36]we use information that we perceive through our senses to help us make decisions, to arrive at beliefs and so on.
[00:29.88]And then there are memory and imagination, which relate to the knowledge of things that happened in the past or may happen in the future. [00:37.98]So, perceiving, remembering, imagining are all internal mental processes that lead to knowing or believing. [00:46.55]Yet each of these processes has limitations, and can lead us to hold mistaken beliefs or make false predictions.
[00:54.44]Take memory, for example. [00:56.11]Maybe you've heard of studies in which people hear a list of related words—[01:01.31]um, let's say a list of different kinds of fruit. After hearing this list, they're presented with several additional words. [01:09.33]In this case, we'll say the additional words were “blanket” and “cherry,” [01:13.59]Neither of these words was on the original list. [01:16.75]And while people will claim correctly that “blanket” was not on the original list, they'll also claim, incorrectly, that the word “cherry” was on the list.
[01:27.04]Most people are convinced they heard the word “cherry” on the original list. [01:32.00]Why do they make such a simple mistake? [01:34.25]Well, we think because the words on the list were so closely related, the brain stored only the gist of what it heard, [01:42.82]for example, that all the items on the list were types of fruit. [01:47.10]When we tap our memory, our brains often fill in details, and quite often these details are actually false.
[01:55.37]We also see this “fill-in” phenomenon with perception. [01:59.94]Perception is the faculty that allows us to process information in the present, as we take it in via our senses. [02:10.25]Again, studies have shown that people will “fill in” information that they thought they perceived, even when they didn’t.
[02:18.29]For example, experiments have been done where a person hears a sentence, but it's missing the word that logically completes it. [02:25.92]They’ll claim to hear that word even though it was never said. [02:29.68]So if I were to say, “The Sun rises in the…” and then fail to complete the sentence, [02:35.80]people will often claim to have heard the word “east.”
[02:39.60]In cognitive psychology we have a phrase for this kind of inaccurate “filling in” of details. [02:45.28]It’s called a “blind spot.” [02:47.55]The term originally referred to the place in our eyes where the optic nerve connects the back of the eye to the brain. [02:54.43]There are no photoreceptors in the area where the nerve connects to the eye, [02:58.99]so that particular area of the eye is incapable of detecting images--[03:03.88]it produces a blind spot in our field of vision. [03:07.12]We aren't aware of it because the brain fills in what it thinks belongs in the image, [03:12.72]so the picture always appears complete to us.
[03:15.68]But the term “blind spot” has also taken on a more general meaning—[03:20.28]it refers to people being unaware of a bias that may affect their judgment about a subject. [03:25.93]And the same blind spot phenomenon that affects memory and perception also affects imagination. [03:32.53]Imagination is a faculty that some people use to anticipate future events in their lives.[03:38.72]But the ease with which we imagine details can lead to unrealistic expectations and can bias our decisions.
[03:46.25]So, um, Peter, suppose I ask you to imagine a lunch salad. No problem, right? [03:53.72]But I bet you imagined specific ingredients. [03:56.91]Did yours have tomatoes? Onion? Lettuce? Mine did. [04:02.24]Our brains fill in all sorts of details that might not be part of other people's image of a salad. Which could lead to disappointment for us--if the next time we order a salad in a restaurant we have our imagined salad in mind, that's not necessarily what we'll get on our plate.
[04:19.47]The problem's not that we imagine things, but that we assume what we've imagined is accurate. [04:25.59]We should be aware that our imagination has this built-in feature—the blind spot—which makes our predictions fall short of reality.