Week 11: Language Flashcards
How is memory for language different from memory for events
- Episodic memory :Memory for events!
-sematic memory: memory of fact
Differences between episodic and sematic memory
- Semantic memory more resistant to forgetting or brain damage than episodic memory
- Retrieval from episodic memory often described as “mental time travel” – re-experiencing events
- Retrieval from semantic memory is often automatic and does not have the same experience
The Lexical Decision Task
- Participants are presented with letter strings that are either words or nonwords, have to make a decision as to which is which
-In this task, accuracy is often at maximal levels (unless participants are pressured to respond very quickly). Therefore, the dependent variable in these tasks is the response time (RT). The core component of these RTs is assumed to be the latency of lexical access
Lexical access is enhanced by:
- Repetition priming – there are faster RTs for repeated words than non-repeated words, even if they are separated by other words.
- Semantic priming – there are faster RTs for words semantically related to the just presented word (e.g. faster RTs for ‘doctor’ after being preceded with ‘nurse’).
What causes priming effects?
® Spreading activation – reading a word increases its activation. Reading a word also increases the activation of related words in the lexicon. This activation decays over time, which is why priming effects are often short-lived
The word frequency effect:
® High frequency words have faster RTs than low frequency words.
® Frequency refers to how common a word is in the natural language. High frequency words are commonly used words, whilst low frequency words are uncommon words.
® This is often quantified by a corpus analysis – counting the frequencies of each word across a large number of texts. Older estimates of word frequency came from books but today there are very large digital databases that are used (e.g. subtitles in films, conversations of twitter)
Estimate of words
- Older estimates of word frequency came from books (Kucera & Francis, 1967)
- Today, there are very large digital databases that are used
- Subtitles in films (SUBTLEX database)
- Conversations on Twitter
implication of word frequency effect
- Word frequency effect implies that HF words are accessed more easily in the mental lexicon
- Some have even argued that the mental lexicon is searched in a serial fashion by word frequency (Murray & Forster, 2004)
- Advantage for HF words is eliminated when words are repeated. Repetition boosts words to their maximum level of activation
Does the word frequency effect really reflect faster reading times for HF words? experiment
- Research in eyetracking says ”yes”!
- Eyetrackers measure where people are looking at on a screen and for how long
- Rayner and Duffy (1986): longer gaze durations to LF words than to HF words while reading sentences
Word frequency effects in memory task
. In recall tasks, there are advantages for high frequency words. However, these advantages only occur in ‘pure’ lists of words (when lists are composed of HF or LF words entirely), and there is little to no frequency effect when mixed lists of HF & LF words are studied (Gillund & Shiffrin, 1984). This is referred to as the mixed-list paradox.
word frequency effect in recognition task
Recognition memory shows an advantage for low frequency words. Low frequency words have a higher hit rate (more ‘yes’ responses to studied words) and a lower false alarm rate (fewer ‘yes’ responses to new words) compared to high frequency words. This pattern is referred to as the mirror effect.
What is the cause of the word frequency effect?
- There has yet to be a single unified explanation of word frequency effects across all tasks
Lexical decision: - Stronger ”base level activation” for HF words
- In other words, HF words are already active from their heavy repetition in language
Free recall: - HF have stronger associations to other HF words, making them easier to learn associations in an experiment
- This is evident in free association data – HF words tend to elicit other HF words
Recognition - HF words are more similar to other HF words, both semantically and in terms of their perceptual characteristics (they have more overlap in their letters and phonemes)
Why are there so many different explanations of word frequency effects?
- Word frequency is correlated with many other variables!
- Word length: high frequency words tend to be shorter
- Concreteness: low frequency words tend to refer to concrete things while high frequency words tend to be abstract
- Neighborhood size: high frequency words have more similar words in the lexicon
- E.g., a common word (e.g., HF) like HOT also has other similar words like TOT, ROT, and POT, but a less common word like COMPUTER doesn’t have as many similar words
Does word frequency even matter on its own? context variability
- Stronger predictor of lexical decision latencies: context variability (Adelman, Brown, & Quesada, 2006)
- Context variability is defined as the number of documents a word occurs in
- E.g., words like “where” or “people” are used across many linguistic contexts, words like “dog” or “baseball” are used in particular contexts
- it is different from word frequency
- A high frequency word that is repeated a lot in one context is a low context variability word
- Likewise, a word could have low frequency overall but appear in a lot of different contexts
Does word frequency even matter on its own? context variability vs word frequency
- Adelman et al. (2006) found that context variability, not word frequency, predicts performance in lexical decision
- Word frequency had almost no effect when context variability was controlled
- High context variability words have shorter RTs than low context variability words
-Almost no effect of word frequency after contextual diversity is controlled
-Clear negative relationship between context variability and RT when word frequency is controlled!
Why would there be such strong context variability advantages?
- Adelman et al. (2006) related these findings to the rational analysis of memory and language by John Anderson
- Rational analysis states that cognition – and memory in particular - is shaped around need probability in the environment
- Recency is one example: we tend to need recent things more than non-recent things, which may be why human memory is centered around recency
- High context variability words are more likely to be needed in future contexts than low context variability words
- Analogy: high context variability words are like tools that can be used in a lot of different situations (e.g., hammer, swiss army knife) – you’re most likely to use these in future situations
- Low context variability words have very specific or niche usages
Context variability and memory
- Studies on context variability were directly motivated by findings that memory benefits for presentation of words in different contexts
- Stronger benefits of repetition when words occur in different contexts (e.g., different backgrounds or font colors) than when presented in the same context
- Stronger memory when repetitions are separated in time than massed consecutively (the spacing effect)
- Similar advantages for low context variability words in language have been found in memory tasks
- Free recall and recognition memory also show advantages for low CD words over high CD words