Sources of Flexibility in Human Cognition: Dual-Task Studies of Space and Language. Focus of Study. What is Flexibility in Human Cognition?

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1 What is Flexibility in Human Cognition? Sources of Flexibility in Human Cognition: Dual-Task Studies of Space and Language An adult human s ability to go beyond an encapsulated method of using geometry to reorient themselves Hermer-Vasquez hypothesized that the bridge between encapsulated and flexible reorientation is the use of spatial language Rob Sanz March 28, 2004 HONR218L This use of spatial language is not only limited to reorientation, but in other cases of spatial memory use as well Nature of the Relationship between Spatial Language Acquisition and Enhanced Ability to Represent Spatial Relationships Advances in spatial language and spatial memory are functionally independent but developmentally linked because they depend on structures that mature at similar times Developmental changes in spatial language and spatial memory might both depend on a common factor Focus of Study Four experiments using a dual-task method with adult humans to test this third possibility An assumption: one cannot use language processing mechanisms to perform two language tasks at once Development of spatial language may produce a change in a child s spatial representations, enhancing their ability to locate themselves or objects in relation to nongeometric characteristics (focus of study)

2 Previous Research Data similar to the Spelke article we studied before the break Adult rats and human children cannot use nongeometric characteristics to reorient themselves in a rectangular room Introduction of landmark helped human adults to reorient themselves more successfully Experiment 1 Verbal Shadowing Replicated Hermer & Spelke s experiment by putting adults into a rectangular room with 4 white walls to see if the adult used the shape of the room (geometric information) to locate a hidden object Used the same room with one blue wall to see if the adult used the presence of the blue wall (non-geometric information) to locate the object Added in verbal shadowing to see if it impaired either of these processes How Does Verbal Shadowing Work? A recording of an experimenter reading political articles from the newspaper was played and the subject was instructed to repeat what they heard Asked to repeat syllable by syllable or word by word rather than waiting for complete syntactic clauses Subjects trained to shadow until they could do it for 2 minutes straight with no pauses longer than 2 seconds at any time Procedure Instructed to find a ring of keys, which they saw being hidden behind one of the 4 corners, after being disoriented by closing their eyes and spinning around in a circle at least 10 times 4 trials with verbal shadowing in room with blue wall 4 trials with no shadowing in room with blue wall 4 trials with no shadowing in room with all white walls Each subject completed all 3 sets of 4 trials What do you expect to happen in each set?

3 Questions Left Unanswered Verbal shadowing involves working memory and attention Therefore, shadowing may have diminished the attention and memory resources that subjects had available to them during the experiment If this is the case, then any interference task that places demands on attention and memory might have an effect on subjects performance Experiment 2 Rhythmic Shadowing vs. Verbal Shadowing Compared the attentional demands of rhythmic and verbal shadowing tasks during a visual search experiment One set of subjects performed the experiment while engaging in verbal shadowing Another set of subjects performed the experiment while engaged in rhythmic shadowing with a nonverbal response (tapping) Another set of subjects performed the experiment while engaged in rhythmic shadowing with a verbal response (repeating nonsense syllables such as do or da ) What is a Visual Search Experiment? Experiment 2A Subjects are asked to tell whether or not a screen full of T s contains the letter L The 3 different types of shadowing were compared to see if they were equal in how much they interfered with the L search task

4 Results for Experiment 2A In 5 of 6 cases, the subjects engaged in verbal shadowing had the highest accuracy rates Reaction times were similar among verbal and rhythmic shadowers Experiment 2B Basically the same as Experiment 1, using verbal shadowing in a rectangular room with 1 blue wall Results show the same decrease in accuracy in locating the object with respect to the nongeometric landmark Rhythmic shadowers commented more than verbal shadowers on the difficulty of the task Experiment 2C Comparison of Shadowing Setup is similar to previous experiments Shadowing technique is rhythmic manual (clapping)

5 Two Possible Conclusions First, adults may use language to combine geometric and non-geometric information Verbally shadowing adults may be able to detect and remember both geometric and non-geometric information but not their conjunction Second, adults may combine geometric and non-geometric information independent of language Verbal shadowing may interfere with adults ability to detect or remember the non-geometric information Experiment 3 This procedure would test if a subject can in fact detect and remember non-geometric information while engaging in verbal shadowing Experiment carried out in a rectangular room with one blue wall, as in Experiment 1 and 2B, with two major changes: First change: object hidden directly behind the wall instead of to the left or right of it Second change: the two short walls and the subject are physically removed from the room These changes are made to ensure that the subject does not rely as heavily on geometric information, but rather associate the location of the object with a non-geometric characteristic Experiment 3 Setup Clarification Predictions If verbal shadowing specifically impairs the ability of the subject to conjoin geometric and non-geometric information, then by removing the geometric information the subject should be able to accurately locate the object since no conjoining of information is necessary (Conclusion 1 from Experiment 2) Results similar to those of Experiments 1 and 2B are expected if verbal shadowing impairs the ability to detect and remember non-geometric information (Conclusion 2 from experiment 2)

6 Procedure Results for Experiment 3 While still shadowing and after being disoriented, subject led out of the room and placed in front of the white and blue wall which are now side by side Subject is then asked behind which wall the object is hidden Questions Left Unanswered This study is an important first step in investigating whether the findings are applicable to other tasks that require combining information from multiple core systems Experiment 4 Verbal Shadowing Without Disorientation The same as Experiment 3, except that now subjects had to distinguish between color and which side of the colored wall the object was hiding behind The subject is not disoriented, so reorientation is not necessary Does language allow for conjoining of geometric and non-geometric information only when subjects are disoriented or does it allow for conjoining in any situation?

7 Results for Experiment 4 Conclusions Introduction of verbal shadowing causes adults to perform similarly to children and rats Suggests that spatial memory system of children/rats is present and functional in adults Suggests that language plays a role in the generation of the flexible spatial performance that is unique to humans Predictions People with language impairment may show reduced flexibility on spatial memory tasks, performing like children Children with language delay may show a delayed transition from the inflexible performance of rats to the flexible performance of humans Prediction on Development Flexibility may emerge over human development not only in spatial memory tasks, but in any task that calls for a combination of information from diverse sources People who speak languages without terms for left or right may show different patterns of performance on spatial memory tasks