From cl+ at andrew.cmu.edu Wed Jul 8 11:03:34 1998 From: cl+ at andrew.cmu.edu (Christian J Lebiere) Date: Wed, 8 Jul 1998 11:03:34 -0400 (EDT) Subject: Negative associations and book news In-Reply-To: <8pcrf=G00Udh0QyE80@andrew.cmu.edu> References: <8pcrf=G00Udh0QyE80@andrew.cmu.edu> Message-ID: \begindata{text, 25043} \textdsversion{12} \template{messages} Luis Botelho asked (in a message that was sent to the act-r-users mailing list but could not be distributed properly): > Hi all, > I would like to know if associations between nodes in ACT-R can take > negative strengths. If so, how do they appear. I mean, what mechanism is > responsible for associations with negative strength? > > -- Luis > ----------------------------- > Lums Miguel Botelho, PhD > Departamento de Cijncias e Tecnologias da Informagco > ISCTE: Instituto Superior de Cijncias do Trabalho e da Empresa > Av. das Forgas Armadas, Edifmcio ISCTE, 2600, Lisboa, Portugal > Tel: 351-1-7903099 > Fax: 351-1-7964710 Negative associations between chunks can of course be set, but they can also be learned. The Posterior Strength Equation (p. 130 of The Atomic Components of Thought - ACT) specifies that associations are equal to the logarithm of a frequency ratio. Since that ratio can be less than 1.0, its logarithm, and therefore the association, can be negative. If the ratio becomes very small, due to the logarithm form the association will in fact become unboundedly negative, effectively acting as an inhibiting connection. That point turns out to be crucial to the lifetime simulation of cognitive arithmetic presented in Chapter 9 of ACT. As you may have gathered from the previous paragraph, the new book about the ACT-R theory, The Atomic Components of Thought, has just been published by Lawrence Erlbaum Associates. It is in fact Erlbaum's special web offer of the month, so order your copy now to take advantage of the discount (except of course workshop attendees who will receive a complimentary copy). For ordering information, you can find a pointer to Erlbaum's web page on the ACT-R home page (http://act.psy.cmu.edu) or you can go directly to http://www.erlbaum.com/spot.htm Happy reading! \enddata{text, 25043} From tkelley at arl.mil Mon Jul 6 12:17:50 1998 From: tkelley at arl.mil (Troy Kelley) Date: Mon, 06 Jul 1998 12:17:50 -0400 Subject: License for ACT-R References: Message-ID: <35A0F8AE.CFE@arl.mil> Hello, My name is Troy Kelley and I work for the Army Research Lab and I am a student at George Mason. My boss, Dr. Laurel Allender expressed the interest to me of using ACT-R within one of our modeling tools called IMPRINT (formally known as HARDMAN and MicroSAINT). I was unsure of the legalities involved with doing such a thing and was hoping someone on this list could help me. Is there a license fee for ACT-R, and if so how much is it? How would our lab go about using ACT-R for our cognitive modeling efforts? Any help on these questions would be appreciated. Troy From ritter at psychology.nottingham.ac.uk Wed Jul 15 15:02:28 1998 From: ritter at psychology.nottingham.ac.uk (ritter at psychology.nottingham.ac.uk) Date: Wed, 15 Jul 1998 20:02:28 +0100 (BST) Subject: Teaching Cognitive Science at CogSci99 Planning Meeting Message-ID: <199807151902.UAA28001@vpsyc.psyc.nott.ac.uk> I thought you might be interested in attending the meeting noted below. You'll hear about it at the conference as well. Cheers, Frank Teaching Cognitive Science at CogSci99 Planning Meeting During the lunch break on 2 August we will have a short (30-40 min.), informal meeting about teaching cognitive science. You should get your lunch, and then meet in the "Inn Wisconsin East" room. We'll try to start about 15 min. into the lunch break to give people time to get food. We will primarily be considering setting up a planning committee to make a proposal to include related activities in next year's Cognitive Science program (such as a tutorial program for attendees and a longer teaching symposium). The committee so far includes Randy Jones, Pat Langley, Frank Ritter, Lon Shapiro, and Richard Young.