Implicit processes II Dr Magda Osman Room 2.25 Office hours Mondays

If there are many failures to replicate evidence of a dissociation between implicit and explicit processes, do you think: A. The evidence for dissociations between E and I processes is problematic B. The methods used to examine dissociation between E and I are problematic C. There is actually no dissociation between E and I processes in the first place

Learning outcomes  Understand what double dissociation approaches to examining implicit processes in clinical populations  Have knowledge of the different clinical populations used to examine the presence of implicit processes  Have knowledge of the variety of methodological approaches used to examine implicit processes in clinical populations

 Patient studies – individuals with neurological impairments  Double dissociations  – Patient 1 shows implicit learning  - Patient 2 shows explicit learning  Neuro-imaging studies – different brain functions associated with different neurological activity The holy grails of compelling evidence:

Clinical Studies  Amnesia  Parkinson’s Disease  Prosopagnosia  Blindsight  Split brain

Amnesia  Knowlton, Ramus, & Squire (1992), Knowlton & Squire (1994, 1996) reported that amnesiacs can perform as well as normals in judging the grammaticality of new strings generated from an artificial grammar, while being very poor at recognizing the training strings. Inconsistency (Knowlton, et al, 1992; Knowlton & Squire, 1996)  Knopman (1991), Nissen and Bullemer (1987), Reber & Squire (1998) showed that also Amnesiacs/ Korsakoff patients could speed up on an SRT task but cannot verbally report the sequence or, indeed, report awareness of the existence of a sequence. Failure to replicate (Curran, 1997; Shanks, Channon, Wilkinson, & Curran, 2005)

Parkinson’s disease  Degenerative disorder – impaired speech and motor behaviour – deficit to the basal ganglia (reward system), memory loss  (Ferraro, Balota, & Connor, 1993; Jackson et al, 1995; Westwater et al, 1998) Show deficits in implicit learning (SRT). Even when the task is presented in verbal form, still leads to poor or no learning. Failure to replicate – show implicit learning in PD patients (Smith, Siegert, McDowall, & Abernethy, 2001) Problematic demonstration of implicit– test of awareness, “if you think there is a sequence say what it is”

Prosopagnosia  Deficit in processing faces; acknowledge that a face is there, but cannot recognize that it is a face, let alone recognizing a familiar face  (De Haan, Young, & Newcombe, 1991; Jones, & Tranel, 2001) – (case studies) – Failed to explicitly identify familiar faces after being presented a whole series during a learning session, but were able to do so implicitly, in one case, this was indicated through galvanic skin responses. Failure to replicate De Haan & Campbell (1991)

Double dissociation  Parkinson’s disease patients show impaired learning on a complex category learning task, despite maintaining good explicit memory about task features (Knowlton, Mangels & Squire, 1996).  In contrast, amnesic patients appear to show normal implicit learning on the same complex category learning task, but poor explicit memory of the task (Knowlton et al., 1996; Reber, Knowlton & Squire, 1996).  Implicit   Explicit   Implicit   Explicit 

But….also…  Parkinson’s disease patients after extensive training, over 3 days, their performance is close to those performing normally (Shohamy, Myers, Onlaor, & Gluck, 2004)  In addition, amnesic patients show equivalent learning to normals on the same complex category learning task, and good explicit memory of the task (Speekenbrink, Channon, Shanks, 2007).  Explicit   Implicit   Implicit   Explicit 

Visual system & Blindsight  Reception of a stimulus in the visual system (Lamme, 2003)  40 ms: V1 activation  80 ms: most visual areas activated  120 ms: visual activation can be found in all cortical areas, including motor cortex (feedforward activation)  Later: recurrent activation among neurons (horizontal, feedforward, feedback) Blindsight (Weiskrantz)  the ability to respond appropriately to visual stimuli in the absence of conscious vision in patients with damage to the primary visual cortex

Blindsight and the Dorsal Stream Patients with lesions to primary visual cortex occasionally retain some visual abilities:  better than chance performance on forced-choice discrimination tasks  spatial navigation and coordination (i.e. avoid obstacles, interact with environment) Thought to be because of other “backdoor” pathways that send signals to the Dorsal Stream, A.K.A the “Where and How Pathway”

Blindsight and the Dorsal Stream  The Dorsal Stream is thought to mediate much spatial processing and interaction with the environment “WHAT” “WHERE”

Blindsight and the Dorsal Stream  The Dorsal Stream is thought to mediate much spatial processing and interaction with the environment  But the neural activity in these structures does not (is not alone sufficient to) enter into consciousness

The Hard Problem Returns  MYSTERY: what is special about neural activity that leads to awareness ? NOBODY KNOWS !

Split-Brain Syndrome  Some cases of severe epilepsy are treated by severing the corpus callosum that connects the two hemispheres of the brain.  The corpus callosum allows information to be exchanged between hemispheres.

Split Brain

 With the exception of smell, each hemisphere receives sensory information and controls movement on the opposite side of the body (contralateral).  But, because of lateralization of some mental processes split-brain surgery can lead to disorders in consciousness.

Split Brain Patient fixates on the mid line. In panel on the right the visual information and the language centres cohere In panel on the left the visual information and the language centres are incoherent

 Can the findings revealing dissociations be explained by procedural artefacts? Many of the findings that show dissociation between Explicit and implicit processes in clinical populations have had problems in being replicated – which raises doubts as to the reliability of the evidence The logic of dissociation suggests that patients have highly specialised and exclusive neurological problems – but this is rarely the case, which suggests this might not be the best approach General questions raised

Is the use of clinical populations a good basis on which to examine dissociation between implicit and explicit processes? A. Yes B. No C. Unsure

Implicit learning  Some research suggested that performance on many implicit learning tasks is unimpaired in patients with neurological damage: E.g. amnesic individuals lack declarative knowledge of task features, but performance equivalent to normals on indirect tests of knowledge  This is taken as evidence for a multiple systems view of learning, in which one is procedural (implicit) and is dissociated from declarative (explicit) learning system. The implicit learning system is designed to monitor the environment for reliable relationships between events (covariations) Is an evolutionary old system – which is also why it may be immune to neurological insult

No Implicit learning Problems with studies showing implicit learning:  Many of the published studies showing implicit learning in neurological patients, shown a numerical advantage for controls  Low statistical power  The explicit measures are not exhaustive  Heavily biased  Relying on null effects  Patients do no only have neurological problem (they are likely to have multiple neurological/psychological deficits)

No Implicit learning Theoretical accounts: (exemplar theories - Nosofsky & Zaki, 1998) (Kinder & Shanks, 2001, 2003; Newell & Shanks, 2014) Often- neurological patients can show learning that is equivalent to healthy age matched controls, given the right learning conditions, and using detailed and fine grained analyses. Neurological damage often leads to slower learning rates, but the learning mechanism appears to be the same for patients and healthy age matched controls

Problems with dualist argument? Wanting their cake and eating it:  Assume dissociable learning mechanisms, but claim that they can interact,  Assume that learning can be implicit and automatic, but assume they are different things, - but supported by the same implicit learning system  Neural localization of different reasoning mechanisms is not tantamount to evidence for qualitatively distinct reasoning systems (Sherry & Schacter, 1987) Why?

Problems with single system argument? Wanting their cake and eating it:  There could be a continuum between implicit and explicit learning processes (Cleermans & Jiménez, 2002) – but this is very difficult to empirically test.  Theorists (e.g. Shanks & St John, 1994) that deny that there are processes that are unconscious are failing to accommodate much empirical research.  The arguments against measures used to examine implicit processes, make it an impossible task to demonstrate unconscious learning.

Summary I  Phenomenal, perceptual awareness  Recurrent interactions in early visual areas: binding, segregation, perceptual organization.  Mammals, birds, reptiles?  Access awareness (introspective)  Recurrent connections to higher centers – executive, memory: putting stimulation in context of current goals. Only then it can be reported.  Humans only (language?)

Summary II Attention without awareness: selection of stimuli which did not reach perceptual awareness Awareness without attention: stimuli may enter perceptual awareness but they do not reach access awareness Only stimuli that reach access (introspective) awareness can be reported.

The last stage seems to be related to consciousness: Recurrent activation among neurons appears to be the key aspect of the brain that corresponds to consciousness Recently Transcranial Magnetic Stimulation (disrupts activity in a particular brain region) – stimulus presented over the threshold may remain invisible; All stimuli above a threshold evoke feedforward activation, but for a conscious experience recurrent activation is necessary. Larger receptive fields as activation spreads -> competition (selection) quality of activity – not a localized centre is the key to consciousness

Which position are you most convinced by? A. Dual system accounts (in which explicit and implicit processes are dissociated) B. Single system account (in which explicit and implicit processes reduce to a single process) C. Single system account that assumes that there are only explicit processes

Critically evaluate clinical evidence that suggests there is a dissociation between implicit and explicit learning processes.