Thursday, 2 June 2016

Sacks on memory

In desperation at Blogger's font sizing I have decided to split the previous post into two. So here's the late Oliver Sacks from his essay "The Lost Mariner":

'There are are no prescriptions,’ Luria wrote, ‘in a case like this. Do whatever your ingenuity 
and your heart suggest. There is little or no hope of any recovery in his  memory. But a man does not consist of memory alone. He has feeling, will, sensibilities, moral being— matters of which neuropsychology cannot speak. And it is here, beyond the realm of an impersonal 
psychology, that you may find ways to touch him, and change him. And the circumstances 
of your work especially allow this, for you work in a home, which is like a little 
world,  quite different from the clinics and institutions where I work. Neuropsychologically, there is little or nothing you can do; but in the realm of the individual, there may be much you can do'.

Tuesday, 1 September 2015

Oliver Sacks on the mind's eye

The late Oliver Sacks, from the New Yorker essay The Mind's Eye, which later morphed into the last chapter of the book of the same name.

Galton’s seemingly contradictory statements  about imagery—is it antithetical to abstract thinking, or integral to it?—may stem from his failure to distinguish between fundamentally different levels of imagery. Simple visual imagery such as he describes may suffice for the design of a screw, an engine, or a surgical operation, and it may be relatively easy to model these essentially reproductive forms of imagery or to simulate them by constructing video games or virtual realities of various sorts. Such powers may be invaluable, but there is something passive and mechanical and impersonal about them, which makes them utterly different from the higher and more personal powers of the imagination, where there is a continual struggle for concepts and form and meaning, a calling upon all the powers of the self. Imagination dissolves and transforms, unifies and creates, while drawing upon the "lower" powers of memory and association. It is by such imagination, such "vision," that we create or construct our individual
At this level, one can no longer say of one’s mental landscapes what is visual, what is auditory, what is image, what is language, what is intellectual, what is emotional—they are all fused together and imbued with our own individual perspectives and values. Such a unified vision shines out from Hull’s memoir no less than from Torey’s, despite the fact that one has become "non-visual" and the other "hypervisual." What seems at first to be so decisive a difference between the two men is not, finally, a radical one, so far as personal development and sensibility go. Even though the paths they have followed might seem irreconcilable, both men have "used" blindness (if one can employ such a term for processes which are deeply mysterious, and far below, or above, the level of consciousness and voluntary control) to release their own creative capacities and emotional selves, and both have achieved a rich and full realization of their own individual worlds.

Friday, 5 June 2015

Aphantasia and SDAM

You know how it is. You wait ages for a paper on innate deficits in mental images and episodic memory, and then two come along in a couple of months.

And a very complementary pair they are.  The more recent of the two, "Lives without imagery – congenital aphantasia" (in Cortex) by Adam Zeman of Exeter and co-authors, discusses the complete, lifelong, absence of voluntary mental images, for which it coins the term aphantasia. The paper is not open access, but a nice summary has been given by Rolf Degen:

Zeman and his colleagues now propose the use of the term ‘aphantasia’ to refer to a condition of reduced or absent voluntary imagery. In the journal "Cortex", they describe, for the first time, the features of their condition,  elicited by a  questionnaire. Participants typically became aware of their condition in their teens or twenties when, through conversation or reading, they realized that most people who ‘saw things in  the mind’s eye’, unlike themselves, enjoyed a quasi-visual experience. 19 of the 21 subjects were male, possibly a tribute to the readership of Discover magazine. 5 reported affected relatives, while 10 stated that all moralities of imagery were affected. More than half of the respondents suffered from impairments of autobiographical memory. The same number identified compensatory strengths  in verbal, mathematical and logical domains.

Despite their substantial or complete deficit in voluntary visual imagery, the majority of participants was at times stricken by involuntary imagery. This could occur during wakefulness, usually in the  form of ‘flashes’ and/or during dreams. When the subjects had to perform task that normally would commandeer imagery - such as  ‘count how many windows there are in your house or apartment’ - they succeeded by drawing on what they described as  ‘knowledge’, ‘memory’  and ‘subvisual’ models.

"Skeptics could claim that aphantasia is itself a mere fantasy: describing our inner lives is difficult and undoubtedly liable to error. We suspect, however, that aphantasia will prove to be a variant of neuropsychological functioning akin to synaesthesia." The latter is usually associated with heightened scores at tests of imagination. How  commonly  does  congenital aphantasia occur?  Existing data suggest a frequency of around 2 percent but there is no fully reported large scale study. "We are optimistic that modern structural and functional brain imaging may help to answer questions about the nature of visual imagery that were first posed in ancient Greece and first quantified at Sir Francis Galton’s breakfast table over a hundred years ago."

The  other (open acess in Neuropsychologia), by Daniela Palombo of Boston University and her co-authors, is about the combination of the absence of images (both voluntary and involuntary) AND the lack of episodic memory, a condition for which it proposes the term "Severely Deficient Autobiographical Memory (SDAM)". 

On the face of it, SDAM is a subset of aphantasia, as some of Zeman et al's respondents had episodic memory impairments and some didn't.

I'll be returning to both of these papers in the weeks to come.

Tuesday, 19 May 2015

Narratives again ... this time from Will Self

In his sympathetic review of Oliver Sacks' new autobiography, On The Move, Will Self remarks:

Oliver Sacks, the eminent neurologist and writer, whose many books have done perhaps more than any other body of work to explain the mysteries of the brain to a general readership, is a strong supporter of the “narrativity” theory of the human subject. Suitably enough – given this is an autobiography – Sacks restates the notion here: “Each of us … constructs and lives a ‘narrative’ and is defined by this narrative.” Elsewhere he asserts: “I suspect that a feeling for stories, for narrative, is a universal human disposition, going with our powers of language, consciousness of self, and autobiographical memory.” Setting to one side the truth or otherwise of this contention (personally I think it’s only the social being that is narrated – to ourselves we are always “such stuff as dreams are made of”), for a man who views his life in dramatic terms, On the Move presents the reader with some quite startling narrative leaps.

Burkeman on Narratives

Fascinating piece by Oliver Burkeman on narratives

Could you have a meaningful life without this sense of continuity, this feeling that you are the person to whom your childhood happened, and who’ll experience your old age? Surely nobody could think of the scenes of their life – childhood summers, first kisses, bereavements – as lacking any connecting thread whatsoever?

But Galen Strawson, another philosopher, says this is exactly how he experiences the world, and he suspects he’s not alone. “I have a past, like any human, [and] I have a respectable amount of factual knowledge about it,” he concedes in Against Narrativity, a 2004 paper highlighted recently by the behavioural scientist Jess Whittlestone. “Yet I have no sense of my life as a narrative with form.”

Friday, 4 January 2013

Wednesday, 2 January 2013

Where's the rest of us ?

Via @OliverSacks' tweet, a superb and moving short article by Dan Levitin  in the Atlantic Monthly on what survives in human beings even when episodic and semantic memory are lost.