Mental Organs

1. Mental Organs

2. Phrenology was an important part of popular culture in Victorian England and in Europe during the 19th century.

3. Four assumptions behind phrenology

4. Assumption 1 Gall assumed that minds were made up of different mental “organs”, each of which is localized in distinct parts of the brain.These include not only basic domains like language and colour but also self-esteem and secretiveness which is distinct from cautiousness .

5. Assumption 2 A further assumption Gall made is that the mental faculties he listed were innate propensities or predispositions to behave or perceive the world in a particular way.

6. Assumption 3 Gall also assumed that each faculty is determined by the content of the information on which it relies, not by the way this information is used to carry out different tasks. We talk about modes of operation to refer to the various ways in which knowledge can be recruited for different kinds of tasks.

7. Memory Modes of operation? Modes of Operation Reason Refers to the various ways in which knowledge can be recruited for different kinds of tasks Classify Attend

8. Gall’s mental faculties were considered by him to be domain-specific, not generalmodes of operation. According to Gall’s taxonomy, there are no mental organs localizable in the brain that are responsible for general abilities like reason, attention or memory.

9. Assumption 4 Finally, Gall assumed that an especially well developed faculty (i.e. mental organ) requires a correspondingly well developed cortical (i.e. physical) organ.Because the bones of an infant are soft and pliable, a highly developed cortical organ will create a protrusion of the adjoining skull that is measurable.

10. What does this view imply about constructs like general intelligence, reason, memory and imagination? Gall:There are no such mental organs (faculties)!

11. So, it is possible on this view to be very gifted in some particular domain of knowledge and yet be congenitally predisposed (predisposed at birth) to be well below average ability in other faculties.

12. It should be clear that Gall was interested in measuring differences in the talents or natural propensities between individuals. So his approach, for better or worse, required him to look for exceptional cases whom he considered either very gifted or seriously deficient in a particular faculty.

13. Domain-specific abilities (for examples, see the accompanying figure) are referred to as verticalfaculties. The function of a vertical faculty is to provide us with a particular kind of knowledge about the world (that’s why we say a vertical faculty is domain-specific).

14. Some examples of cross-modal perceptual representations that we investigate still exist in psychology. For example, this object directs your visual attention to the right side of space, but also movements will occur faster in this direction, as will your response to sound when occurring on your right as opposed to your left. Our representation of space integrates a number of modalities.

15. For Gall, there is no specific mental organ for memory, nor for any of the Aristotelian faculties. Rather, each separate biological cortical organ has its own special memory. Similarly, there was no organ for the ‘Intellect’. In other words, Intellect could not be neurologically localized and so was not a biologically plausible category. Instead, each mental organ had its own intelligent mode of functioning.

16. The goal of modern psychology is to understand the details of mental computations in a particular domain, so we need to go well beyond Gall’s notion of mental organs.

17. The term we now use, modularity, refers to the idea that complex neural systems responsible for some task (e.g. understanding a sentence) are organized into subcomponents -- modules -- which are functionally independent of one another. This principle of modularity makes very good sense when processing tasks are very complicated (like sentence comprehension). In non-modular systems, a small change to improve one part (whether by natural selection in the case of the brain or by a human designer in the case of a machine) would have consequences (often undesirable) in many other places.

18. Dissociation Methodology Modular System A Modular System B

19. PRINT HOW CAN WE IDENTIFY THE ACTUAL MODULES OF MIND? Letter Identification Semantic System Orthographic Lexicon Grapheme- phoneme conversion rules Phonological Lexicon SPEECH OUTPUT

20. PRINT OOK IS PRONOUNCED ‘UK’ B IS PRONOUNCED ‘BUH’ B-O-O-K IS ‘BOOK’ BOOK LEOPARD PINT HAND LEXICAL Letter Identification NONLEXICAL VOOK Semantic System Orthographic Lexicon Grapheme- phoneme conversion rules FOR READING A DANGEROUS FELINE PREDATOR A MEASURE OF VOLUME FOR LIQUID BODY PART Phonological Lexicon SPEECH OUTPUT

21. TASK 1: READ ALOUD YINT, GOOP, SIFE, LUNK ETC. TASK 2: READ ALOUD PINT, ACHE, BEAD, BOTH, ETC. OKAY OKAY PHONOLOGICAL DYSLEXIA IMPAIRMENT TO NONLEXICAL ROUTE SURFACE DYSLEXIA IMPAIRMENT TO LEXICAL ROUTE WE ALWAYS MEASURE IMPAIRMENT RELATIVE TO A GROUP OF NORMAL CONTROLS

22. 100% Surface Dyslexic A classic double dissociation Phonological Dyslexic Accuracy Normal Control 50% Pronounceable Nonsense words Exception words

23. 100% Surface Dyslexic This is not a classic double dissociation Phonological Dyslexic Accuracy Normal Control Why not? 50% Pronounceable Nonsense words Exception words

24. 100% Surface Dyslexic This is not a classic double dissociation Phonological Dyslexic Accuracy Normal Control Why not? 50% Pronounceable Nonsense words Exception words Patient A is better than Patient B on Task X. Patient B is better than Patient A on Task Y.

25. PHONOLOGICAL AND SURFACE DYSLEXIA TOGETHER MAKE UP A DOUBLE DISSOCIATION BETWEEN THE LEXICAL AND NON-LEXICAL READING ROUTE. THE EXISTENCE OF THESE TWO READING DISORDERS PROVIDES EVIDENCE THAT THESE TWO ROUTES FROM PRINT TO SOUND ARE SEPARATE FUNCTIONAL COMPONENTS (MODULES) OF THE READING SYSTEM. ANOTHER WAY TO STATE THIS IS THAT THE LEXICAL AND NON-LEXICAL READING ROUTES ARE DOUBLY DISSOCIABLE.