# \[video\] A beginners guide to Bayesian Cognitive Modelling

**URL:** <https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025>\
**Category:** Probabilistic Programming\
**Tags:** announcement\
**Created:** [February 25, 2021, 4:05pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025 "2021-02-25T16:05:09Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![drbenvincent](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/drbenvincent/32/3046_2.png) [@drbenvincent](https://discourse.julialang.org/u/drbenvincent)\
**Post date:** [February 25, 2021, 4:05pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025/1 "2021-02-25T16:05:09Z")

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Just in case people here are interested, here is a video of a seminar talk I was invited to give to the Psychology department at the University of Leicester, UK. I go through some examples using Julia and Turing. As well as a simple linear regression example, I give examples of two Bayesian cognitive models:

1. Delay discounting in a decision making experiment
2. A Bayesian optimal observer model of a visual attention experiment

Video: [A beginners guide to Bayesian Cognitive Modelling - YouTube](https://www.youtube.com/watch?v=NNySqCSmIo4) [45 mins]  
GitHub repo: [GitHub - drbenvincent/2021-Leicester-seminar: Code for a seminar talk at University of Leicester, UK](https://github.com/drbenvincent/2021-Leicester-seminar)

PS: If you like this kind of thing, then you can retweet this 🙂 [https://twitter.com/inferencelab/status/1364962838196977667?s=21](https://twitter.com/inferencelab/status/1364962838196977667?s=21)

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**Author:** ![BradGroff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bradgroff/32/21156_2.png) [@BradGroff](https://discourse.julialang.org/u/BradGroff)\
**Post date:** [February 25, 2021, 5:29pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025/2 "2021-02-25T17:29:55Z")

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Hi @drbenvincent, very cool talk!

One question: what is `@.`? I looked in turing and distributions for macros but didn’t see anything matching. Thanks!

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**Author:** ![carstenbauer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/carstenbauer/32/4981_2.png) [@carstenbauer](https://discourse.julialang.org/u/carstenbauer)\
**Post date:** [February 25, 2021, 5:31pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025/3 "2021-02-25T17:31:52Z")

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Its a convenience macro that broadcasts every operation to its right, i.e. `@. a = b + c * d` becomes `a .= b .+ c .* d`.

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**Author:** ![devel-chm](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/devel-chm/32/3572_2.png) [@devel-chm](https://discourse.julialang.org/u/devel-chm)\
**Post date:** [February 25, 2021, 5:36pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025/4 "2021-02-25T17:36:49Z")

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@. is `@ __dot__ ` which is searchable in the documentation.  
The search for @. or “@.” was not helpful or productive.

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**Author:** ![BradGroff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/bradgroff/32/21156_2.png) [@BradGroff](https://discourse.julialang.org/u/BradGroff)\
**Post date:** [February 25, 2021, 5:52pm UTC](https://discourse.julialang.org/t/video-a-beginners-guide-to-bayesian-cognitive-modelling/56025/5 "2021-02-25T17:52:49Z")

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@carstenbauer @devel-chm thanks both! I guessed it was related to the normal `.` usage but it’s very handy to know for sure and also [where](https://github.com/JuliaLang/julia/blob/750f42aac2ad09b9ccd79408ee4e19941f668fa4/base/broadcast.jl#L1214-L1216) to find it!

So, it seems like ` __dot__ ` is handled as an exceptional case by the parser [here](https://github.com/JuliaLang/julia/blob/30afc32fc919e7238ec29aa18b0efb1ea5e5db66/src/julia-parser.scm#L1623-L1625) and this is unique case (I cannot find any other dunders in there).