Jeff Hawkins,
in his 2004 book On Intelligence, proposed the
so-called memory and prediction theory
of how human intelligence arises. The basic idea of Hawkins’ theory of
intelligence, in his own words, is as follows:
The
brain uses vast amounts of memory to create a model of the world. Everything we
know and have learnt is stored in this model. The brain uses this memory-based
model to make continuous predictions of future events. It is the ability to
make predictions about the future that is the crux of intelligence.
Kurzweil's recent (2012) theory (or model)
of the how our brain functions has many ideas in common with those in Hawkins'
book. Moreover, there is also some discussion over credit sharing. I quote from
Kurzweil (2012): 'The pattern recognition theory of mind that I present here is
based on recognition of patterns by pattern recognition modules in the
neocortex. These patterns (and the modules) are organized in hierarchies. I
discuss below the intellectual roots of this idea, including my own work with
hierarchical pattern recognition in the 1980s and 1990s and Jeff Hawkins (born
in 1957) and Dileep George's (born in 1977) model of the neocortex in the early
2000s'.
Hawkins
pointed out in his book that the neocortical memory differs from that of a
conventional computer in four ways:
1. The cortex
stores sequences of patterns. For
example, our memory of the alphabet is a sequence of patterns. It is not
something stored or recalled in an instant, or all together. That is why we
have difficulty saying it backwards. Similarly our memory of songs is an
example of temporal sequences in memory.
2. The cortex
recalls patterns auto-associatively.
The patterns are associated with themselves. One can recall complete patterns
when given only partial or distorted inputs. During each waking moment, each
functional region is essentially waiting for familiar patterns or
pattern-fragments to come in. Inputs to the brain link to themselves
auto-associatively, filling in the present, and auto-associatively linking to
what normally flows next. We call this chain of memories, thought.
3. The cortex
stores patterns in an invariant form.
Our brain does not remember exactly
what it sees, hears, or feels; the brain remembers the important relationships
in the world, independent of details.
4. The cortex
stores patterns in a hierarchy.
Storing
sequences, auto-associative recall, and invariant representation are the
necessary ingredients for predicting the future, based on memories of the past.
How this happens is the subject matter of Hawkins’ book. According to him,
making such predictions is the essence of intelligence.
Hawkins takes
the view that perhaps consciousness is simply what it feels like to have a neocortex.
He suggests that the self-awareness aspect of consciousness is synonymous with
the formation of declarative memories.
These are memories we can recall and talk about.
Hawkins, while
formulating his theory of intelligence, took very seriously the so-called Mountcastle’s hypothesis. Since the same
types of layers, cell types and connections exist in the entire cortex,
Mountcastle (1978) had put forward the following hypothesis:
There
is a common function, a common algorithm, that is performed by all the cortical
regions.
What makes the
various functional areas different is the way they are connected. He went further to suggest that the reason why the
different functional regions look
different when imaged is because of these different connections only. Hawkins
suggests that, although hearing, touch, vision etc. are processed by the same
algorithm in the neocortex, they are handled differently in the R-brain: ‘Hearing
relies on a set of audition-specific subcortical structures that process
auditory patterns before they reach the cortex. Somatosensory patterns also
travel through a set of subcortical areas that are unique to somatic senses.
Perhaps qualia, like emotions, are not mediated purely by the neocortex. If
they are somehow bound up with subcortical parts of the brain that have unique
wiring, perhaps tied to emotion centres, this might explain why we perceive
them differently, even if it doesn’t explain why there is any sort of qualia
sensation in the first place’.
The structure
of the inputs (i.e. the spatio-temporal information pattern) is qualitatively
different for, say, the auditory nerve and the optic nerve. The optic nerve has
a million fibres, and the auditory nerve has only thirty thousand. The optic
nerve caries information that is more spatial than temporal, and the auditory
nerve carries information that is more temporal than spatial. This may have a bearing
on why is red red and green green. No matter how consciousness is defined,
memory and prediction play crucial roles in creating it.
Here is how
Hawkins answers why our thoughts appear to be independent of our bodies: ‘To
the cortex our bodies are just part of the external world. Remember, the brain
is in a quiet and dark box. It knows about the world only via the patterns on
the sensory nerve fibers. From the brain’s perspective as a pattern device, it
doesn’t know about your body any differently than it knows about the rest of
the world. There isn’t a special distinction between where the body ends and
the rest of the world begins. But the cortex has no ability to model the brain
itself because there are no senses in the brain. Thus we can see why our
thoughts appear independent of our bodies, . .’.
I end this post by stating two points made by Kurzweil (2012) regarding
the brain model described above.
The first is that Dileep George also contributed to this model: 'In 2003
and 2004, PalmPilot inventor Jeff Hawkins and Dileep George developed a
hierarchical cortical model called hierarchical temporal memory'.
The second point is that Hawkins' model differs in some important aspects
from the model presented by Kurzweil in his 2012 book: ' . . . As the name
implies, Hawkins is emphasizing the temporal (time-based) nature of the
constituent lists. In other words, the direction of the lists is always forward
in time. His explanation for how the features in a two-dimensional pattern such
as the printed letter "A" have a direction in time is predicated on
eye movement. He explains that we visualize images using saccades, which are
very rapid movements of the eye of which we are unaware. The information
reaching the neocortex is therefore not a two-dimensional set of features but
rather a time-ordered list. While it is true that our eyes do make very rapid movements,
the sequence in which they view the features of a pattern such as the letter
"A" does not always occur in a consistent temporal order. (For
example, eye saccades will not always register the top vertex in "A"
before its bottom concavity.) Moreover, we can recognize a visual pattern that
is presented for only a few tens of milliseconds, which is too short a period
of time for eye saccades to scan it. It is true that pattern recognizers in the
neocortex store a pattern as a list and that the list is indeed ordered, but it
may also represent a spatial or higher-level conceptual ordering . . .'.
Dileep George's 2008 doctoral dissertation presents a more up-to-date
description of the hierarchical temporal memory method [Dileep George, 'How the Brain Might
Work: A Hierarchical and Temporal Model for Learning and Recognition' (PhD dissertation, Stanford University, June 2008)].
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