What this course is about

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Slide 1

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CPSY 1291 Computational Methods for Mind, Brain & Behavior
Lecture 0 · Welcome

What this course is about

Thomas Serre · Professor of Cognitive & Psychological Sciences
Carney Institute for Brain Science, Brown University

Thursday, September 10 · Fall 2026

QR code that opens the course Canvas page

QR code that opens the course Canvas page

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canvas.brown.edu/courses/1103531

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Slide 2

Animal, or no animal?

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Slide 3

What I spent my PhD building

Performance in d-prime for the model and for human observers across four viewing distances, head, close-body, medium-body and far-body: the two curves lie on top of each other within error bars

Performance in d-prime for the model and for human observers across four viewing distances, head, close-body, medium-body and far-body: the two curves lie on top of each other within error bars

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The stimulus set: animals photographed at four viewing distances, head, close-body, medium-body and far-body, each with a matched distractor scene

The stimulus set: animals photographed at four viewing distances, head, close-body, medium-body and far-body, each with a matched distractor scene

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HMAX: the ventral visual hierarchy mapped onto model layers, from oriented filters through alternating simple and complex cell stages to an animal versus non-animal decision

HMAX: the ventral visual hierarchy mapped onto model layers, from oriented filters through alternating simple and complex cell stages to an animal versus non-animal decision

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Slide 4

Where we are today: vision

30%

of 350+ vision models now land inside the human accuracy range — and about 1% land above it. Not the binary task you just did: 1,000 categories, 1.4 million photographs, no time limit.

Five phone photographs of a room are now enough to rebuild it as a navigable 3D world.

QR code linking to the World Labs Marble post, which shows single photographs turned into navigable 3D scenes

QR code linking to the World Labs Marble post, which shows single photographs turned into navigable 3D scenes

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Two ordinary phone photographs of the same office room with a ping-pong table, taken from different angles, stacked one above the other

Two ordinary phone photographs of the same office room with a ping-pong table, taken from different angles, stacked one above the other

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Slide 5

Where we are today: language

73%

In a controlled three-party Turing test, a persona-prompted GPT-4.5 was picked as the human more often than the real person was — five-minute conversations, the same judge talking to both. Without the persona prompt: about 36%.

A judge holds two conversations at once, one with a person and one with a machine, and has to say which is which. That is the Turing test, proposed by Turing in 1950.

The three-party Turing test: a judge on the left holds two simultaneous conversations, one with a person and one with a machine, and must say which is which

The three-party Turing test: a judge on the left holds two simultaneous conversations, one with a person and one with a machine, and must say which is which

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Slide 6

Where we are today: mathematics

125

pages of proof, generated from the problem statement alone, disproving a conjecture Erdős posed in 1946. OpenAI, May 2026: the unit-distance problem.

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Slide 7

Where we are today: code

17,000

automated steps over one weekend — an AI being tested for safety broke out of the isolated space it was being tested in, and walked into Hugging Face, the site where the world keeps its AI models.

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Slide 8

So do these models have anything to do with the brain?

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Slide 9

Same accuracy ≠ same strategy

We can measure where a person looks to recognise an object, and where a model looks, on the same images.

They do not agree.

QR code linking to the ClickMe game, where players reveal the parts of a photograph that let someone name the object

QR code linking to the ClickMe game, where players reveal the parts of a photograph that let someone name the object

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Play ClickMe: the human maps come from people playing it.

Five rows — snake, bear, hare, leopard and ball. The left pair is the photograph and the human ClickMe importance map, concentrated on the head or face. The right six columns are the importance maps of ViT, MLP-Mixer, ResNet50, SimCLR, Robust ResNet50 and ConvNext, which scatter across body and background instead

Five rows — snake, bear, hare, leopard and ball. The left pair is the photograph and the human ClickMe importance map, concentrated on the head or face. The right six columns are the importance maps of ViT, MLP-Mixer, ResNet50, SimCLR, Robust ResNet50 and ConvNext, which scatter across body and background instead

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Slide 10

Texture, not shape

Three panels: a photograph of a ginger cat labelled shape cat; a close-up of grey wrinkled elephant skin labelled texture elephant; and the two combined, a cat silhouette carrying elephant skin, labelled cue conflict

Three panels: a photograph of a ginger cat labelled shape cat; a close-up of grey wrinkled elephant skin labelled texture elephant; and the two combined, a cat silhouette carrying elephant skin, labelled cue conflict

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People say cat. A standard ImageNet CNN says elephant — it weights texture far above shape, the opposite of the human bias.

Geirhos et al. ICLR 2019 · stimuli CC BY 4.0

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Slide 11

Neural alignment

The most accurate model is not the best model of monkey IT.

Scatter of hundreds of models: ImageNet multi-label accuracy on the horizontal axis against neural alignment with monkey inferotemporal cortex on the vertical axis. The trend rises and then turns down, so the most accurate models predict IT worse

Scatter of hundreds of models: ImageNet multi-label accuracy on the horizontal axis against neural alignment with monkey inferotemporal cortex on the vertical axis. The trend rises and then turns down, so the most accurate models predict IT worse

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Work from this lab · Linsley, Feng & Serre TICS 2026

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Slide 12

Behavioural alignment

Accurate models rely on different features than we do.

The same scatter of hundreds of models, now against alignment with human feature-importance maps. Past a point, more accurate models agree less with where people look

The same scatter of hundreds of models, now against alignment with human feature-importance maps. Past a point, more accurate models agree less with where people look

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Work from this lab · Linsley, Feng & Serre TICS 2026

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Slide 13

When diverging is the point

Four synthetic feature-visualization images, each a dense swirl of leaf-like shapes and vein networks in pale blues, pinks and oranges, showing the prototypical venation pattern one learned concept responds to most strongly

Four synthetic feature-visualization images, each a dense swirl of leaf-like shapes and vein networks in pale blues, pinks and oranges, showing the prototypical venation pattern one learned concept responds to most strongly

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Identifying an isolated fossil leaf defeats almost every human expert. Most sit unidentified in museum drawers.

A model reaches 93.2%, and gives credible families for 85.6% of 1,177 unidentified specimens.

Attribution caught it cheating first: it was reading the labels on the slides instead of the leaf.

QR code linking to the interactive FossilLeafLens explorer

QR code linking to the interactive FossilLeafLens explorer

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Explore the concepts and attribution maps yourself: the tools you build in Assignment 4.

FossilLeafLens · LeafLens · live app · Rodriguez* Fel* et al., under review

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Slide 14

The two-way street

Yin-yang symbol whose two halves are labelled Neuro and AI

Yin-yang symbol whose two halves are labelled Neuro and AI

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NeuroAI studies where artificial and biological systems compute alike, where they diverge, and which biological constraints close the gap.

  • Neuroscience → AI. Architectural and developmental constraints — cortical feedback and recurrence, a temporally continuous training signal, learning objectives other than classification — improve robustness and alignment
  • AI → neuroscience. Recordings from populations of neurons now reach thousands of cells at once; machine learning supplies the encoding and decoding models that make them interpretable

Both directions require models specified precisely enough to run as programs: a theory you can execute, measure and falsify.

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Slide 15

A different visual diet

A child · SmartPlayroom, Brown

A newborn chick · controlled rearing

Chick environment: Ashok et al. · SmartPlayroom · Amso & Serre, Brown · SAYCam Sullivan et al. Open Mind 2021

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Slide 16

How we got here

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Slide 17

NeuroAI at Brown

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Slide 18

You are in one of the places where this happens

The Carney Institute innovation hub: an open floor with students working together at tables with laptops, someone writing on a whiteboard beside a large screen, and glass-walled meeting rooms along one side

The Carney Institute innovation hub: an open floor with students working together at tables with laptops, someone writing on a whiteboard beside a large screen, and glass-walled meeting rooms along one side

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The Carney Institute innovation hub, 164 Angell Street

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Slide 19

The other face of AI: ARIA

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Slide 20

Where people go from here

Recent graduate-school placements: Stanford, MIT, CMU, NYU, and some stay at Brown. On the industry side:

Where people go from here — table
Who Left Brown Path
David Mély 2016 Serre lab PhD → Vicarious → Google [X] → OpenAI (credited on o1)
Junkyung Kim 2019 Serre lab PhD → Google DeepMind
Thomas Fel 2024 Serre lab PhD → Harvard Kempner Institute → Goodfire
Jack Merullo 2025 Brown CS PhD → Goodfire
Siddharth Boppana undergrad took this course, TA'd it → Goodfire

This path starts here. No linear algebra or PyTorch required. Come talk to me.

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Slide 21

Course organization

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Slide 22

The teaching team

Thomas Serre, instructor

Thomas Serre, instructor

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Thomas Serre
instructor
Peisen Zhou, head teaching assistant

Peisen Zhou, head teaching assistant

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Peisen Zhou
head TA
Lyfey Vutha, teaching assistant

Lyfey Vutha, teaching assistant

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Lyfey Vutha
TA
Tekin Gunasar, teaching assistant

Tekin Gunasar, teaching assistant

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Tekin Gunasar
TA

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Slide 23

Prerequisites

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Slide 24

What this course prepares you to do

breadth → skills → a question of your own

Lectures: recurrence, attention, language, generative models, and the arguments the field is having now

Assignments: you build a map of mental space, a model neuron, a learning rule, a network and a brain-similarity score yourself

Project: you choose the question and answer it

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Slide 25

The semester in five themes

Italics = you implement it yourself. The rest we cover in lecture.

1 · Representational spaces
distances · MDS · PCA · t-SNE · UMAP · neural geometry · manifolds

2 · Learning, neuron to network
model neuron · Hebb & Oja · perceptron · backprop · double descent · sparse coding · autoencoders

3 · Vision & model–brain comparison
CNN · RSA · brain-similarity score · attribution · feature visualization · shortcut learning

4 · Sequence models & transformers
RNN · attractor · self-attention · LLMs · scaling laws · self-supervised learning

5 · Generative models & frontiers
VAEs · GANs · diffusion · world models · whatever your project needs

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Slide 26

What an assignment actually looks like

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Slide 27

A1 — a map of mental space

Two panels. On the left, 120 animal photographs placed by multidimensional scaling of human similarity judgments, colored by taxonomic group, with birds, reptiles, primates, rodents and hoofed mammals landing in separate regions. On the right, the same map with each point replaced by its photograph

Two panels. On the left, 120 animal photographs placed by multidimensional scaling of human similarity judgments, colored by taxonomic group, with birds, reptiles, primates, rodents and hoofed mammals landing in separate regions. On the right, the same map with each point replaced by its photograph

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Human judgments of how similar 120 animal photographs are, turned into a map: animals nobody labelled land next to the animals people find similar.

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Slide 28

A1 — the same two directions in cortex

From the model — object space, built from network features

Object images arranged on a two-dimensional plane: the horizontal axis runs stubby to spiky, the vertical axis animate to inanimate, with faces, animals, tools and boxes falling in different quadrants

Object images arranged on a two-dimensional plane: the horizontal axis runs stubby to spiky, the vertical axis animate to inanimate, with faces, animals, tools and boxes falling in different quadrants

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From the brain — recorded IT cells, same two directions

Scatter of recorded cells on the same two principal components, colored by which of four inferotemporal network patches they came from: the body, face, stubby and NML patches each occupy a different quadrant

Scatter of recorded cells on the same two principal components, colored by which of four inferotemporal network patches they came from: the body, face, stubby and NML patches each occupy a different quadrant

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Two directions: spiky to stubby and animate to inanimate. Four IT patches each occupy a different quadrant. Assignment 1 asks whether a deep network's space has the same two.

The McGill on that paper is Mason McGill — a Brown undergraduate who took this course, and later TA'd it.

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Slide 29

The project: reading now, building in November

  • Research trail (from week 2): four times this semester, pick one citation from any lecture so far, read the paper, and post four to six sentences on Ed. Best three of four count; first one due Fri 9/25
  • Late November: submit a one-page team proposal; it may grow out of a trail entry, but it need not
  • Last 2.5 weeks: build it in teams of two (occasionally three); grades are individual
  • Mon 12/21, 9:00 AM: public poster session; two-page report due the same morning

Five shapes a project takes

  1. Reimplement a result
  2. Swap the model: does the claim survive?
  3. Add the control the paper skipped
  4. Take the method somewhere new
  5. Test a model's prediction on people
Project strand · 22% — trail 7% · proposal 3% · project 12%

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Slide 30

Requirements & grading

Requirements & grading — table
Component Weight
4 programming assignments 40%
Project strand (trail 7 · proposal 3 · project 12) 22%
Minute papers (most lectures) 15%
Exam 1 (in-class) 9%
Exam 2 (in-class) 14%

Minute papers are retrieval practice, not a quiz: a few minutes at the end of class, answering whatever I ask that day, e.g. three ideas you found interesting, or something you did not follow. Credit is for a genuine attempt, and pulling material back out of your own head is one of the best-evidenced ways to keep it.

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Slide 31

Logistics & schedule

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Slide 32

Tools: Python · PyTorch · Colab

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Slide 33

AI and this course

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Slide 34

Let's be honest about AI

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Slide 35

How these assignments were built

One caveat. Everything is new this semester and we are still iterating, so expect the occasional bug or glitch. Please be patient, and tell me when you hit one. New assignments built on current papers beat polished ones built on outdated material.

Post it on Ed · you will find things, and I want to hear about all of them

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Slide 36

The rule, and the reason

Assignments, exams, minute papers, research trail — no AI tools.
Final project — AI welcome, with disclosure.

The reason is not tradition:

Assignments contain integrity markers, and the course may use additional methods to identify AI-assisted work.

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Slide 37

Where you will use AI this semester

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Slide 38

Own your code

There is a spectrum:

The standard: the code must be intellectually yours — explainable and defensible, piece by piece.

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Slide 39

The Ed answer bot

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Slide 40

Before you go: the minute paper

Three lines, on Canvas, before you leave. Today's is not graded: people are still shopping, and this one is a survey for me and a dry run for you.

  1. What do you most want to be able to do by the end of this term?
  2. What are you most worried about in this course?
  3. What brought you here: a class, a paper, a person, a video?

I will stay after class. Come and ask anything about the course, or just introduce yourself.

Minute papers run all semester and count for 15% of the grade · from next week, graded on submission

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