1. Cognitive Operations What does the brain actually do? Some possible answers: –“The mind” –Information processing… –Transforms of mental representations –Execution of mental representations of actions

2. First Principles “cognitive operations are processes that generate, elaborate upon, or manipulate representations” –As patterns of activity in one or more neurons –We often lack conscious access to these representations –Neuroscientists still know very little about how information is represented in the brain

3. Mental Representations Mental representations can start with sensory input and progress to more abstract forms –Local features such as colors, line orientation, brightness, motion are represented at low levels How might a neuron “represent” the presence of this line?

4. Mental Representations Mental representations can start with sensory input and progress to more abstract forms –Local features such as colors, line orientation, brightness, motion are represented at low levels

5. Mental Representations Mental representations can start with sensory input and progress to more abstract forms –texture defined boundaries are representations arrived at by synthesizing the local texture features

6. Mental Representations Mental representations can be “embellished” - Kaniza Triangle is represented in a way that is quite different from the actual stimulus -the representation is embellished and extended

7. Mental Representations Mental Representations can be transformed –Rubin Vase, Necker Cube are examples of mental representations that are dynamic

8. Mental Representations Mental Representations can be transformed –Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process Mentally rotate the images to determine whether they are identical or mirror-reversed SAME MIRROR-REVERSED

9. Mental Representations Mental Representations can be transformed –Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process

10. Mental Representations Mental Representations can be transformed –Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process

11. Mental Representations Mental Representations can be transformed –Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process

12. Mental Representations Mental Representations can be transformed –Shepard & Metzlar (1971) mental rotation is an example of transforming a mental representation in a continuous process –The time it takes to respond is linearly determined by the number of degrees one has to rotate –Somehow the brain must perform a set of operations on these representations - where? how?

13. Mental Representations Mental Representations can be transformed into abstract information representations –Posner letter matching task –Are these letters from the same category (vowels or consonants) or are they different?

14. Mental Representations Mental Representations can be transformed into abstract information representations –Posner letter matching task –Are these letters from the same category (vowels or consonants) or are they different? –Are they physically the same or are they the same in an abstract way - they are in the same category? A AaAa AUAU SCSC ASAS SAME DIFFERENT

15. Mental Representations Mental Representations can be transformed into abstract information representations –Posner letter matching task –Participants are fastest when the response doesn’t require transforming the representation from a direct manifestation of the stimulus into something more abstract

16. Mental Representations Mental Representations can be representations of actions –response selection and response inhibition –when one of several responses is required, each response is pre-programmed and the appropriate one is selected –In Go/No-Go tasks when the same response is made repeatedly on Go trials its representation is difficult to override on No-Go trials

17. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour

18. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour RED

19. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour BLUE

20. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

21. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour RED

22. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour BLUE

23. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

24. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

25. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour GREEN

26. Mental Representations Mental Representations can interfere –Stroop task: name the colour in which the word is printed (I.e. don’t read the word, just say the colour –The mental representation of the colour and the representation of the text are incongruent and interfere –one representation must be selected and the other suppressed –This is one conceptualization of attention

27. Mental Representations These are some examples of how a cognitive psychologist might investigate mental representations The cognitive neuroscientists asks: –where are these representations formed? –What is the neural mechanism? What is the code for a representation? –What is the neural process by which representations are transformed?

28. First Principles What are some ways that information might be represented by neurons?

29. First Principles What are some ways that information might be represented by neurons? –Magnitude might be represented by firing rate –Presence or absence of a feature or piece of information might be represented by whether certain neurons are active or not – the “labeled line” theory –Conjunctions of features might be represented by coordinated activity between two such labeled lines –But these are just brainstorming suggestions…little is known about how information, especially complex representations and representations in memory are actually encoded

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