Tampilkan postingan dengan label Cognitive. Tampilkan semua postingan
Tampilkan postingan dengan label Cognitive. Tampilkan semua postingan

Selasa, 25 April 2017

Cognitive psychology and architecture of mind



Cognitive psychology perceives human mind as a biological information processing system developed by evolution, whereas computer is man-made information processor.  Aaron Slomanphilosopher and researcher on artificial intelligence and cognitive science wrote in the article titled, TheArchitecture of Brain and Mind “Biological information processing systems produced by evolution still far outstrip both our understanding and our practical achievements: there are deep gaps in our theories and in our engineering capabilities.”

Computational theory of mind and cognitive architecture
The computational theory of mind is the view that the human mind is an information processing system and that thinking is a form of computing. This view is common in modern cognitive psychology and is presumed by theorists of evolutionary psychology. The design on mind’s information processing components and systems is called cognitive architecture. According to this concept the distinction between short-term memory system and long-term memory system is architectural distinction just like the distinction between a house and a church.   
Some theorists argue that mind is built from independent processing modules. Each module is specialized for a particular function such as recognizing human faces or speech. An alternative point of view is that the building blocks of the mind are flexible, general-purpose mechanisms that perform many diverse functions.  Long-term memory system is one such general purpose mechanism in that it stores mental representations of both faces and speech sounds from the past to enable recognition in the present and future.
Symbolic models of mind
Symbolic model of mind
There are two models for the architecture of mind, symbolic and connectionist. The symbolic models assume that the mind is built like a digital computer. Pioneering works on computers by von Neumann in the late 1950s provided the foundation for such models. The data in a computer are processed according the rules of a program. The symbolic models of cognitive processes assume that mental representations are symbols that are serially processed by a set of rules, just as the computers do. Herbert A Simon, father of artificial intelligence and Nobel Prize winner wrote: “ The Physical  Symbol System Hypothesis states  that  a system will  be capable of  intelligent  behaviour if  and only if  it  is a physical symbol system. A physical symbol system is a system capable of inputting, outputting, storing, and modifying symbol structures, and of carrying out some of these actions in response to the symbols themselves.” (Page 3 Invariants of Human BehaviourThis class of architecture posits a centralized control system over the information process of the mind. The sensory input is received in the sensory memory store and immediately transferred to the short-term working memory store. The short-term working memory store is the central controlling system of the information processing. From the short-term working memory store some are selected for output as behaviour and others are transferred to long-term memory store. From the long-term memory store some are retrieved to the short-term working memory system for processing.
Connectionist model of mind
Connectionist model of mind
Instead of looking to the digital computer, connectionist models try to use the structure of the brain itself as a model of the mind’s structure. Connectionist models are based on associations among the numerous simple units of brain cells called neurons. The central nervous system comprising of brain and spinal cord is composed of one trillion (1012) neurons. Every neurons is connected to other neurons through dendrites and axons which are the connecting organs extending from the cell body. The dendrites of a single neuron may receive as many as 10,000 connections from other neurons. The connection junctions are called synapses.
Neural networks and connectionism
Through synaptic connections the neurons in the brain form neural networks. A neural network is composed of a group or groups of functionally associated neurons. The knowledge of neural networks in the brain has inspired the cognitive scientists to evolve the theory of connectionism.
Connectionism is a set of approaches in the field of artificial intelligence, cognitive psychology, cognitive science, neuroscience and philosophy of mind, which models mental or behavioural phenomena as the emergent processes of interconnected networks of simple units. There are many forms of connectionism, but the most common forms use neural network models.

Rabu, 05 April 2017

Cognitive aspects of language Reading disability


Two years ago a boy of 9 years studying in the fourth class of an English medium school was brought to me for correction of his scholastic backwardness and behavioural abnormalities such as disobedience, temper tantrums and reluctance to go to school. Previously he was diagnosed by a clinician as ‘childhood schizophrenia’ and given a psychotropic drug. The condition did not improve even after six months’ medication. On examination he was found to be suffering from reading disability (dyslexia) and associated emotional problems.
Treatment for dyslexia consists of using educational tools to enhance the ability to read. Medicines and counseling are usually not used to treat dyslexia. An important part of treatment is educating the child and the family about the condition.  
Reading disability or dyslexia is the most common form of learning disability. Dyslexia is a Specific Learning Disability [SLD]. A child with dyslexia cannot read correctly and comprehend accurately what is read. Dyslexia is different from reading difficulties resulting from other causes such as deficiency with vision or hearing, or from poor or inadequate reading instruction. National Institute of Neurological Disorders and Stroke [NINDS]  under National Institute of Health, USA defines dyslexia as follows: “Dyslexia is brain-based type of disability that specifically impairs person’s ability to read. These individuals typically read at levels significantly lower than expected despite having normal intelligence.”
The features of disorder varies from person to person but the common characteristics among people with dyslexia are difficulty with sound processing, spelling, and/or rapid visual-verbal responding. In children these deficiencies are expressed as scholastic backwardness and behavioural abnormalities.
When the onset of dyslexia is in adulthood, it usually occurs as a result of brain injury or with the onset of dementia. Dyslexia can be inherited in some families, and recent studies have identified a number of genes that may predispose an individual to develop dyslexia
Dyslexia is not an intellectual disability. Cognition of an individual develops independently. Therefore Intelligence Quotient (IQ) and dyslexia are not interrelated.
Characteristics of dyslexia
I. Symptoms in Preschool-aged children
It is difficult to identify dyslexia before the child begins school. Parents who keenly observe their children may notice the following symptoms:
1.    Delays in speech
2.    Slow learning of new words
3.    Difficulty in rhyming words as in nursery rhymes
4.    Knowledge of letters does not improve
5.    Letter reversal or mirror writing. Example: "Я" instead of “R”
II. Symptoms in early primary school children
1.    Slow in learning the alphabet
2.    Inability to associate sounds with the letters that represent them. In other words sound-symbol correspondence is difficult
3.    Difficult to identify rhyming words or lack of phonological awareness
4.    Inability to segment words into phonemes or sound blocks (lack of phonemic awareness)
5.    Naming-speed deficit: naming-speed refers to how quickly an individual can tell the names of a set of familiar objects. For example a student may be shown 50 patches of different colours and asked to name the colours quickly. Individuals with dyslexia find it difficult to name even the familiar colours.
6.    Inability to distinguish between similar sounds in words and mixing up sounds in polysyllabic words. Examples: “aminal” for animal, “cutbis” for biscuit
III Symptoms in older primary school children
1.    Slow or inaccurate reading
2.    Very poor spelling which is called dysorthographia.
3.    Very slow in reading out loud, reading words in the wrong order, skipping words and sometimes saying a word similar to another word.
4.    Difficult to associate individual words with their correct meanings
5.    Difficult to keep time when doing certain task
6.    Children with dyslexia fails to see similarities and differences in letters and words, and may be unable to sound out pronunciation of an unfamiliar word
7.    Tendency to omit or add letters or words when writing and reading.
IV Symptoms in secondary school children and adults
Some people with dyslexia are able to disguise their weaknesses, even from themselves. Many students reach higher education before they encounter the threshold at which they are no longer able to compensate for their leaning disability. At this stage dyslexic people are identified by writing that does not seem to match their level of intelligence. Dyslexic people often substitute similar-looking, but unrelated, words in place of the ones intended. Examples: what/want, say/saw, help/held, fell/fall, to/too, who/how etc.
Associated disabilities and disorders
Many other learning disabilities often occur in association with dyslexia, but it is not clear whether these learning disabilities share the same neurological causes with dyslexia. These disabilities include:
Dysgraphia: This disorder expresses itself primarily through writing or typing. Dysgraphia is often multifactorial. It may be due to impaired letter-writing automaticity and impaired visual word form which makes it more difficult to retrieve the visual picture of words from long term memory, required for spelling.
Dyscalculia: It is a neurological condition characterized by a problem with basic sense of number and quantity. People with this disorder often can understand very complex mathematical concepts and principles but have inability to memorize basic mathematical facts involving addition and subtraction.
Attention deficit disorder: Dyslexia is often associated with ADD and ADHD. These are dealt with separately.
Cluttering: This is a disorder of speech fluency. Both rate and rhythm of speech are defective resulting in erratic, non-rhythmic, rapid and jerky spurts of words that usually contain faulty phrasing.
Causes of dyslexia
Researchers have and are evolving many theories on the causes of the dyslexia. These theories are not mutually contradictory but enlightening on the different causative factors of this disorder.
Effect of language orthography
The complexity of a language’s orthography can be a significant contributing factor to the difficulties experienced by dyslexic readers. Orthography is the writing system of a language. There are deep orthographies and shallow orthographies. Arabic and English are examples of deep orthographies that do not have a one-to-one correspondence between sound blocks (phonemes) and the letters that represent them. Shallow orthographies have a one-to-one relationship between graphemes (meaningful letter blocks) and phonemes and the spelling of words is very consistent. This type of writing is called phonetic orthography. Most of the East European languages like Albanian, Bosnian, Bulgarian etc. and many Asian languages are phonographic. Most of the Indian languages including Malayalam have phonemic orthographies.  Deep orthographies contribute more to the difficulties of a dyslexic reader. Logographic writing systems like Japanese and Chinese characters have graphemes that are not directly linked to their pronunciation pose different types of dyslexic difficulty.
From a neurological perspective, different types of writing system, for example alphabetic as compared to logographic writing systems, require different neurological pathways in order to read, write and spell. Because different writing systems require different parts of the brain to process the visual notation of speech, children with reading problems in one language might not have a reading problem in a language with a different orthography. The neurological skills required performing the tasks of reading, writing, and spelling can vary between different writing systems and as a result different neurological deficits can cause dyslexic problems in relation to different orthographies.
Incidentally, the boy who was brought to me two years back is having not much reading problem with his native language Malayalam.
Aggravating conditions
Dyslexia is attributed to neurological factors that influence the individual's ability to read, write, and spell written language.The following conditions may be contributory or overlapping factors, as they can lead to reading disability:

  1. Aphasia - neurologically based speech disorders, which can cause alexia (acquired dyslexia).
  2. Attention deficit hyperactivity disorder - A disorder that occurs in between 12% and 24% of those with dyslexia.
  3. Auditory processing disorder - A condition that affects the ability to process auditory information. Auditory processing disorder is a listening disability. Some children can acquire auditory processing disorder as a result of experiencing otitis media, a condition characterized by bacterial infection with fowl smelling discharge.
  4. Developmental dyspraxia - A neurological condition characterized by a marked difficulty in carrying out routine tasks involving balance, fine-motor-control, difficulty in the use of speech sounds, problems with short term memory and organization are typical of dyspraxics.
  5. Specific language impairment (SLI) - A developmental language disorder that can affect both reading and writing. SLI is defined as “pure” language impairment, meaning that is not related to or caused by other developmental disorders, hearing loss or acquired brain injury.
Management
There is no cure for dyslexia. But dyslexic individuals can learn to read and write with appropriate educational support. Early intervention is very helpful. Stress and anxiety contribute to the difficulties of dyslexic. So stress management and alleviation of anxiety are essential.  
A cognitive technique for undergraduates is reading the first and the last sentences of each paragraph first, comprehending them and then reading the whole paragraph. This technique enhances the comprehension of the entire paragraph. It has been found that training focused towards visual language and orthographic issues yields longer-lasting gains than mere oral phonological training.