A New Approach Parameterization of Cognitive Disabilities

Ivo Ramos Maia Martins*1, María Fernanda Cabrera-Umpiérrez*2, Maria Teresa Arredondo*3, Ana María Navarro Cerdá2

*Life Supporting Technologies, ETSIT- UPM Avda. Complutense 30, Madrid, Spain

1iramos@lst.tfo.upm.es 2chiqui@lst.tfo.upm.es

3mta@lst.tfo.upm.es #Asociación ITACA

Instituto ITACA, Universidad Politécnica de Valencia. Camino de Vera s/n. 46022. Valencia (Spain) 2annacer@itaca.upv.es

Abstract— This paper focuses on the description of the approach used to parameterize the cognitive user models developed under the FP7 EU Founded project VERITAS: Virtual and Augmented Environments and Realistic User Interactions To achieve Embedded Accessibility DesignS. The methodology defined consists on the identification of standards, rules and guidelines found on the literature to categorize the cognitive attributes. To complete the parameterized cognitive user model it was created a relationship between ACT-R parameters, the affected tasks and the cognitive parameters. A research on existing ACT-R models is still being carried out in order to obtain functions and values that can be suitable for the VERITAS parameterized cognitive user models table. The development of the previous method will provide useful information to complete this parameterization. Futures steps will consist on the integration of the parameterized cognitive user models into the virtual user models.

I. INTRODUCTION

Nowadays there is a continuous ageing of the European population. It is very important to provide the maximum of independence to elderly people and people with cognitive impairments such as cognitive ageing, Alzheimer and Parkinson Disease. The development of products and services accessible to everyone is the correct way to achieve the population requirements in the future.

With this objective, VERITAS project is aiming to operationalize and revolutionize the accessibility testing at all stages of creation of new products in the considered five industrial domains (Automotive, Smart Living Spaces, Workplaces, Infotainment and Healthcare) ¡Error! No se encuentra el origen de la referencia..

The goal is to introduce simulation-based and virtual reality testing at all stages of the design process in order to ensure that future products and services can be “universally” used, including people with disabilities and elders. For creating VR tools with high acceptability amongst users, not only physical, but also cognitive and psychological models that represent the cognitive capabilities should be integrated in the design process.

Different theories of human cognitive & psychological modelling and interaction should be therefore integrated and

validated within VERITAS, focusing on those models that can represent the different cognitive, psychological and perception processes of elderly, cognitive impaired and physical impaired people.

In order to create cognitive models of the target users that can be used within VERITAS accessibility tools, it is necessary to identify which are the cognitive and psychological functions and corresponding parameters (e.g. reaction time, perception, attention, working memory, etc.) that are related with the defined VERITAS cognitive impairments and to define recommendations, guidelines and values that will support the designers and developers’ decisions at the moment of creation of new products and services.

Our paper will focus on the methodology used to define the relevant cognitive parameters within the context of VERITAS. The use of existing models of the cognitive architecture Adaptive Control of Thought-Rational (ACT-R) and the relationship with existing medical studies are the main focus of our study.

II. STUDY DESCRIPTION & METHODOLOGY The study description will help to understand the context of

this study within VERITAS project as well as the used methodology for modeling VERITAS users.

A. VERITAS User Modelling Methodology

Virtual user modelling is considered as the core research issue in VERITAS. The virtual user models will be generated based on existing standards and guidelines but also based on a multisensorial platform designed and implemented within VERITAS that will “sense” the needs of real users with disability by measuring their behaviour in simulated environments [1].

Since, virtual user modelling with disabilities is considered a very challenging task which is not yet fully developed, not even at research level, VERITAS will follow an innovative approach of generating virtual user models based on combining the results of three different but complementary (in most of the cases) approaches. Thus the Virtual user

modelling process of VERITAS consists of the following steps:

- Abstract User Models (AUM) creation that can be implemented within VERITAS based on Analysis of existing models, medical studies, guidelines, methodologies and existing practices, User needs and well known accessibility guidelines and standards. An AUM represents the different facets of a disability.

- Appropriate Task models implementation, based on UIML/USIXML language, when users performing specific tasks and interactions

- Iterative update and verification of the models using the implemented VERITAS multisensorial platform.

- Generation of Generic Virtual User Models (GVUM), by merging the Abstract User Model with the affected tasks per disability.

- Creation of the Virtual User Models, by instantiating the GVUM, which represents a specific user with a disability/s.

In the following scheme, the steps followed in VERITAS for creating a model can be seen:

Figure 1 - Representation of the architecture of the VERITAS SP1,

methodology to create the virtual user models

Ontologies will be used to provide a powerful and growing specification of the abstract user models. An abstract user model stored in the ontology will include the type of user disability, user capabilities, user needs, characteristics from cognitive user models, physical user models, behavioural & psycholological user models, guidelines and standards.

In the following sections, each element of this schema will be further detailed under the cognitive perspective.

B. Abstract Cognitive User Models

An Abstract User Model (AUM) is a descriptive representation of the different dimensions of a human being. In Veritas, a cognitive abstract user model of each cognitive disability categorizes the representative features of the cognitive and psychological facets of an individual: definitions, types, cognitive functional limitations that may

generate, including relevant parameters, measurements and metrics found in literature and computational modelling approaches.

These models will be - in a second step - refined with the Multisensorial platform. The Multisensorial platform is used to fine tune the virtual models with the result of the interaction of real users and the virtual environments and to provide feedback for quantitative evaluation and verification of the user models [1]. 

On one hand, an initial research was made in order to determine the most relevant cognitive processes in the context of the cognitive disabilities to be used for representation of the abstract cognitive user models. These processes were divided in two major groups: basic and higher-level processes.

The basic cognitive processes are composed by reaction time, attention (which is subdivided in selective, divided and sustained), memory (subdivided in semantic, episodic, procedural and working) and perception (subdivided in visual, auditory and haptic).The higher-level group is composed by decision making, orientation, and speech and language [2].

Once the relevant cognitive processes were selected, the following step was to determine how the different cognitive disabilities - Alzheimer, Parkinson and cognitive ageing - affects on the cognitive processes. With this aim, a deep research in medical literature was performed. Table 1 represents the change or affect of the cognitive processes in the normal elderly, early DAT, and early PD. The losses are qualitatively indicated by the + sign. A greater number of crosses indicate a more pronounced degree of severity [2].

TABLE I COGNITIVE PROFILES OF THE ELDERLY AND PATIENTS WITH DEMENTIA OF

ALZHEIMER’S TYPE (DAT) AND PARKINSON’S DISEASE (PD)

On the other hand, under the perspective of VERITAS domains (Automotive, Smart Living Spaces, Workplaces, Infotainment and Healthcare), existing approaches (mainly computational and cognitive architecture models such as ACT-R, GOMS, GOMS-Simple, ACT-Simple, EPIC, SOAR, PUM, ANNs, Fuzzy Logic and Markov) that address and/or model aspects of the cognitive processes were analyzed [2].

A state of art with the strengths and weaknesses of these modeling approaches was performed. This analysis pointed out ACT-R as the most promising and extended modelling approach, that is consistent with the Abstract User Model intended in VERITAS: an explicit descriptive model of human cognition and behaviour that can be afterwards parameterized. In the following section a complete analysis of ACT-R as reference cognitive architecture will be shown.

C. The ACT-R research approach

The cognitive architectures are theories to simulate and understand how the human mind works. They are based on cognitive psychology theories and assumptions and are implemented in a computer program that uses knowledge representations to reproduce the human thinking [3] .

The Adaptive Control of Thought-Rational (ACT-R) was the selected cognitive architecture to obtain the missing values and parameters for the different disabilities. It provides a conceptual framework for the creation of the models of how people will perform the tasks. It reproduces assumptions about the human cognition based on facts resultant from psychology experiments. ACT-R uses a modular organization, which means that the cognition emerges from the interaction of independent modules, each of them is related with a function and specific regions of the brain (Figure 2)[2].

Figure 2 - ACT-R 6.0. Each ACT-R module is associated with a function

Different models written in ACT-R are created per each task. Beside the incorporation of the ACT-R’s view of cognition it is necessary to incorporate assumptions about the particular task. The veracity of these assumptions can be

measured by comparing the results of the model with the results of people doing the same task [2].

ACT-R is a hybrid cognitive architecture: its symbolic structure is a production system, whereas the subsymbolic structure is represented by a set of massively parallel processes that can be summarized by a number of mathematical equations, with parameters. The subsymbolic equations control many of the symbolic processes. For instance, whether (or how fast) a fact can be retrieved from declarative memory depends on subsymbolic retrieval equations, which take into account the context and the history of usage of that fact.1

ACT-R architecture allows, through the subsymbolic structure with parameters, and the symbolic structure (task models) the generalization of new situations, users and domains, which means that allows a wide variation among models.

D. Cognitive moderators in ACT-R: Disabilities as overlays

An overlay is a technique for including a theory of how a moderator (ie: aging) influences cognition across all models within a cognitive architecture [4]. An overlay is an adjustment or set of adjustments to the parameters or mechanisms that influence all models implemented in the architecture to reflect changes due to an altered mental state or due to long term changes such as development [5]. The main idea of an overlay is to change the architecture in such a manner that the behavior of all models developed under that architecture will be affected.

In many architectures, such as the one described here, ACT-R, there are a set of mechanisms and a number of parameters that play a role in the model’s functioning; an overlay will modify a combination of parameters and mechanisms to represent situation specific but relatively long acting changes to information processing. For example, an eyeglasses overlay would allow more inputs to be passed to the vision processor; a caffeine overlay could increase processing speed by 3% and improve vigilance by 30% [4]. Overlays are based on popular theories and studies about cognitive and behavioural moderators that can be applied to cognitive architectures. The goal is to specify mechanisms that can be implemented within the architecture or changes to current mechanisms to simulate the effect of the cognitive impairments on embodied cognition.

These theories are typically not cast as additions to the knowledge necessary to perform a task (it would mean creating a cognitive model), but are described as changes to how people process information under a psychological state. Thus, they make suggestions about process, about how the mechanisms of embodied cognition change across all tasks under this facet.

In the case of VERITAS, an analysis was performed in order to determine these overlays: the values of the parameters (from the subsymbolic structure) per cognitive disability that

1 http://act-r.psy.cmu.edu/about/

were related with the cognitive processes (high level and low-level) detected in the AUM.

After that, a wide literature research has been conducted in order to extract the values of these parameters for the different VERITAS end-users: elderly and cognitive impaired in different domains.

For example, the ACT-R parameter activation spread (:ga) of the goal module is related with the VERITAS basic cognitive process memory. According with the research made so far it is possible to say that the value of the activation spread parameter (:ga) for moderate Alzheimer is 0,68.

Currently, an ongoing research is focusing on extracting production task models that correspond to the primitive cognitive task models defined in VERITAS,

The final development of the ongoing research will provide useful information to complete the parameterized cognitive user models. One of the major difficulties is the large unpredictability and variability that different persons with the same cognitive problem can have while performing the same task. To improve the obtained results, would be necessary a large research in collaboration with psychologists and users in order to develop ACT-R models per each task.

E. Virtual User Models

The creation of Virtual User Models is considered as the core research issue in VERITAS. They will be generated from an instantiation of the Generic Virtual User Models [6].

Their creation is based on the result of the unification of the Abstract User Models, the collection of parameters, the ACT-R productions that are related with the primitive tasks, the result of the measurements and the feedback of real users obtained with the Multisensorial Platform.

Figure 3 - Process of creation of the Virtual User Model

The Generic Virtual User Models will be used by the user model generator to create instances of the Virtual User Models per each application scenario (Figure 3) [6].

The Virtual User Models will be described with the use of ontologies for the representation of the Abstract User Models and UIML/USIXML files for the association of the virtual users with tasks. The final step is their inclusion on the simulation platform in SP2 (Innovative VR models, tools and simulation environments) [7].

III. RESULTS

Table II shows the list of the ACT-R (sgp) parameters found so far in literature and medical studies that are connected with VERITAS primitive tasks and cognitive processes.

TABLE II RELATION BETWEEN ACT-R (SGP) PARAMETERS AND VERITAS COGNITIVE

PARAMETERS

The ACT-R parameters listed in the table II, intrinsically

(meaning at a subsymbolic level) correspond to a specific ACT-R module (Figure 2), which, at the same time, are related with the different cognitive processes relevant for VERITAS previously described.

Literature has shown that two disabilities may share the same parameters and value – for instance, medical literature shows that Parkinson and Alzheimer at level 1 have the same CRD value –. In those cases, we can use analogy to transfer the value of the corresponding ACT-R parameter of a specific disability (Alzheimer) to the same parameter of the other disability (Parkinson).

The use of results from medical studies is then a useful way to obtain values for overlaying the equations that represents the cognitive processes.

So far we have 5 ACT-R (sgp) parameters related with cognitive ageing, 12 related with Alzheimer’s disease and 5 related with Parkinson’s disease. All these values are related as well with the VERITAS cognitive processes and primitive tasks.

IV. CONCLUSIONS AND NEXT STEPS

Though the study is not yet finalized, so far we are able to conclude that it is possible to find ACT-R studies related with the VERITAS cognitive parameters which will be relevant to model VERITAS end-users with cognitive impairments. Mostly, the parameters are values and ranges.

It is also important to refer that with the research in medical studies related with the disabilities previously referred, we were able to find values (i.e. CDR of Alzheimer studies with

the Parkinson’s disease) that were useful to use as well in the ACT-R modelling process.

Finally, it has to be mentioned that to improve the obtained results and to extract missing values, a large research in collaboration with psychologists and users would be necessary in order to develop ACT-R models per each task.

ACKNOWLEDGMENT

Authors thank the VERITAS consortium for their contribution to this work.

REFERENCES [1] VERITAS project (IST- 247765) Annex I- Description of Work 2009. [2] V. Kolodyazhniy, M. Delahaye, Mariya Goranova Valkova, Karel Van

Isacker, Andrean Lazarov, Maria de las Mercedes Fernandez-Rodriguez, Tamara Aguilar, Rocío Zaragoza, Ana Navarro, Juan Carlos Naranjo, Héctor Galán. VERITAS project (IST- 247765) Deliverable D1.4.1 - Abstract Cognitive User Models 2010

[3] Anderson, J., Bothell, D., Byrne, M., Douglass, S., Lebiere, C., & Qin, Y. (2004). An integrated theory of the mind. Psychological Review, 111(4):1036–1060.

[4] Ritter, F. E., Reifers, A. L., Klein, A. C., & Schoelles, M. J. (2006). Lessons from defining theories of stress. In W. Gray (Ed.) Integrated Models of Cognitive Systems. New York, NY: Oxford University Press.

[5] Jones, G., Ritter, F. E., & Wood, D. J. (2000). Using a cognitive architecture to examine what develops. Psychological Science, 11(2), 93-100.

[6] Hans-Joachim Wirsching. VERITAS project (IST- 247765) Deliverable D1.6.1 - Implementation of VERITAS virtual user model platform 2010.

[7] Abel Serra, Juan Carlos Naranjo and Ana María Navarro, Eleni Chalkia. VERITAS project (IST- 247765) Deliverable D1.6.2 - UIML/USIXML task modelling definition 2010.