Prática de Shadowing: What Is Jev? The AI Model That Doesn't Generate Text - Aprenda a falar inglês com vídeo

all right i want to talk about jev jev's a new ai model from a startup called type safe

and it's a bit unusual because it's an ai model

that doesn't actually write any text it actually answers questions by picking from a list

and then giving a probability for each one of his answers

now type safe calls this a new type of ai model it's a system one model

which is a name borrowed from Daniel Kahneman in his book one of my favorites thinking fast

and slow Kahneman describes two modes of thinking human thinking

that is and the first of those modes is called system one thinking

and system one thinking is fast and automatic

so what's two times two you instantly know the answer is

four without having to really work it out in your head that's system one thinking the other type

of thinking is classified as system two thinking and that's slow

and deliberate so

if i ask you what's 17 times 24 well you're probably going to need to work through

that one step by step to figure it out

or just look at the answer on your teleprompter

which is uh 408 there we go got it now most

of the ai models we use are built to write stuff

and a chatbot produces its answers one token at a time

in a ford pass now a reasoning model goes a bit further than

that and it actually writes out its chain of thought as we're going through this

so you can actually kind of see what it was thinking

which is basically as close to a system two model as ai gets

but but a lot of decisions inside software are not really system two they're just kind of quick judgment calls

so let me give you an example of that let's say

that we have got a email for customer support and

that email says that I was charged twice this month please fix it all right

so how do we respond to this email well the software

that's handling this email probably has to look at three types

of question one of the questions is is this a refund request yes

or no another question might be

which team needs to process this email maybe the billing team

or maybe it's the technical support team or maybe it's the sales team

and then also how urgent is this request how quickly do we need to respond

now a person just skimming an email like that they would instantly know

that refund yeah it's yes this is a refund request that's kind of a system one bit of work

and it's that kind of work that jev is built for

so a common way to automate a support email problem like

this today using an llm would be to send this email to the llm

and ask for the answers back the answers to these things in a structured format

so maybe we would go through this large language model output some tokens

and these tokens would represent a format maybe in json now

that mostly works

but it doesn't come back with a reliable sense of how

sure the model is how confident is a large language model

that it got the answer to these questions right well we could ask the model

but whatever it responds with wouldn't necessarily actually match the real

probabilities the model used to come up with this answer

but jev well jev does come up with probabilities so

if we send these questions to JEV we're going to get a very different looking response

so it takes in two things it takes in what's called state

which is the data the decision is about so

that might include our support email

that might include some recent customer charges as well all of

that is input into the JEV model

and it also takes in each of these questions as well into the model as input

and our three questions are actually three different types of questions so refund that is a yes

or no question

which type safe calls a null a team this team question it really comes down to a choice as to

which team is this so picking one option from a list

and then urgent

that really comes down to a score on a scale from

low to critical now all three of these questions go in in a single request

and whereas an llm would write its json answer out one token at a time jeff doesn't generate any text

so all three answers they all come back at once

and that's a big part of why this is so much faster

and cheaper than an llm on these types of questions now

we provide questions as input what is coming back i said

jeff doesn't give you text what it gives you coming back our probabilities as the output

so for refund it's going to be a single number let's

say it's going to come back with 0 .9 meaning there is a 90 chance that yes this is a

refund request for the team it's a probability for each one of the options that were part of this choice.

So for example, the billing choice, which is one of the three, may come back with a probability score of 0 .85.

And by the way, the answer to choice can only be the options that we give it.

So for team, it's always going to be billing or technical or sales.

And then urgency, well, that's going to come back if we kind of put this on a scale, pretty high to critical here so this is quite important.

Now, the model can still pick the wrong options or score any of these questions incorrectly,

of course, but the probability tells us how likely that is.

So how do you train a model to give accurate probabilities like this?

Well, let me go back to training traditional LLMs for a moment.

Most language models, they start with a stage known as pre -training.

So you pre -train a model first.

That means the model reads a huge amount of text and it learns to predict the next token.

Now that creates a model that knows a lot of stuff but it isn't much use to talk to yet.

So if we want to use this as a chatbot then we need to go to a second stage, which is called post -training.

Now, a lot of post -training uses a technique called reinforcement learning.

The model produces an answer, something scores that answer, and the model kind of gets nudged towards the answers that score well.

so the question is what's doing the scoring well one way to do that is with a technique called rl

hf reinforcement learning from human feedback

so people are doing the scoring there human raters look at two responses from the model

and they pick the one they like best

and those choices train a reward model and then

that chatbot is going to be trained to give answers

that the reward model scores highly people tend to like answers

that sound confident so an unfortunate side effect of rlhf is

that a model can learn to sound like really sure of itself even

when it's wrong

but that's just one form of reinforcement learning another form is r l v r that's reinforcement learning with verifiable rewards.

And the scoring here is automatic.

100

Did the model get the right answer to the math problem?

101

Does the code it wrote pass its unit tests?

102

Those sort of things.

103

And that's a big reason that reasoning models today have got so good at math and coding.

104

But the reward here only checks whether the final answer was right.

105

It doesn't reward the model for knowing how sure it should be.

106

And those models spend a

107

while working through their chain of thought before they come up with an answer

108

and that can make them a little bit slow and expensive to run.

109

Now JEV is trained with a different form of reinforcement learning.

110

It's called RLCD, reinforcement learning for calibrated decisions.

111

Now TypeSafe haven't published much about JEV's architecture

112

so i'll stick to what they have said well we know that jeff gives a probability

113

for each option and it's rewarded when those probabilities turn out to be right

114

so that's what the C is all about it's saying the model is calibrate it.

115

And a model that's calibrated kind of basically looks like this.

116

So along the bottom axis here if we map probability

117

and then along the side axis here we can map whether the model is correct.

118

So a well calibrated model is going to have kind of a diagonal line much like this.

119

So when we say that there is a 80 probability that 80 probability is going to be correct about 80

120

of the time that's calibration so back to the the refund question

121

that was the first of the three questions we posed to jeff about

122

that support email so

123

if we have probabilities we can use them to inform code using a threshold like this

124

so we've got a probability threshold here one is certainty zero is definitely not kind of thing

125

so if a probability score is above let's say 0 .9

126

so maybe our score comes back here somewhere

127

that means we can treat this support email as a legit refund request

128

and we can send that straight to the refund queue for processing

129

if however the score comes back anywhere kind of around between here and let's say 0 .1

130

well there's some uncertainty here so the code

131

that received a number like this would know to actually get a human involved

132

so now we need to bring in a person to actually check

133

that because we're not sure and

134

if a score comes in below 0 .1 well i think we can say that's not a refund request

135

so keep calm and carry on we don't need to do anything with that one because the numbers are calibrated,

136

the threshold also tells us roughly how often the automatic path will be wrong.

137

So the more a mistake is going to cost, the higher we would set the threshold.

138

Now this works for more than support emails of course.

139

Jeff can act as a guardrail

140

that can be used around all sorts of things like around a chat bot that's checking messages going in

141

and out for things like well jailbreak attempts

142

but there are limits jev only takes text in as of today it's not very good at math

143

or even counting so you're going to want to leave

144

that stuff to something else

145

and like any ai model it can be tricked by instructions hidden in the data it's reading

146

so is it time to throw away large language models

147

and replace them completely with system one models no hardly

148

but the two can work together so

149

if you think about a workflow maybe we have jev in the workflow

150

that can make quick calls like sorting

151

that customer support email to see whether it's a refund or not

152

and then in the workflow we could go to a large

153

language model to do the slower work work like replying to the customer

154

and then we could go back to use Jev to classify any response

155

that came back from the customer

156

which is pretty much how Danny Kahneman said we work too

157

most of what we do runs on those fast automatic system one processes

158

so that's these two stages here and then the slow and careful system two, which is the large language model in this case,

159

that only kicks in when something needs real thought.

160

Oh, and I wanted to share a thing about the name of Jev as well.

161

Jev is named after William Stanley Jevons, who was an economist who pointed out in 1865

162

that as steam engines got more efficient britain actually used more coal that's known as jevons paradox

163

so perhaps the same thing will happen with system one models

164

when a judgment call is super fast

165

and super cheap like with jev well it can go into places where an llm would be too slow

166

or too expensive today like in every row of a database or on every line of a log file. Who knows?

167

All right, that's Jev.

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Where would a System 1 model fit into the software that you work on?

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Let me know in the comments.

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Vocabulário e dicas de fala para esta lição

Este vídeo tem 169 frases e 2101 palavras para praticar shadowing. A fala dura 14:51. O falante mantém um ritmo estável de cerca de 141 palavras por minuto, confortável para o shadowing. 85% das palavras estão entre as 3.000 mais comuns do inglês; vale a pena estudar o restante antes de começar.

Vocabulário principal deste vídeo

15 palavras do vídeo que vale a pena aprender, com pronúncia e significado:

Palavra	Pronúncia	Significado
probability substantivo	/ˌpɹɑ.bəˈbɪl.ə.ti/	probabilidade
refund substantivo	/ɹɪˈfʌnd/	reembolso
reward substantivo	/ɹɪˈwɔɹd/	recompensa
token substantivo	/ˈtoʊkən/	símbolo, sinal
automatic adjetivo	/ˌɔː.təˈmæt.ɪk/	automático
threshold substantivo	/ˈθɹɛʃ(h)oʊld/	umbral, soleira
mathematics substantivo	/mæθ(.ə)ˈmæt.ɪks/	matemática
format substantivo	/ˈfɔːɹ.mæt/	formato
technique substantivo	/tɛkˈniːk/	técnica
output substantivo	/ˈaʊtpʊt/	produção
judgment substantivo	/ˈd͡ʒʌd͡ʒ.mənt/	juízo, julgamento
instantly advérbio	/ˈɪnstəntli/	instantaneamente
urgent adjetivo	/ˈɜː.d͡ʒənt/	urgente
axis substantivo	/ˈæksɪs/	eixo
necessarily advérbio	/ˌnɛs.əˈsɛɹ.ə.li/	necessariamente

Phrasal verbs que você vai ouvir

Palavra	Significado
come back verbo	voltar
come up with verbo	pensar (em), alcançar
throw away verbo	deitar fora, jogar fora

Gramática neste vídeo

As estruturas que o falante mais usa, com as palavras exatas do vídeo:

Estrutura	No vídeo
Voz passiva be + particípio passado — o foco está no que acontece, não em quem faz	is called · is classified · are built
Orações relativas who / which + oração — informação extra sobre uma pessoa ou coisa	choice, which is · stage, which is · two, which is
Present perfect have/has + particípio passado — uma ação passada que ainda importa agora	haven't published · have said

Pronúncia para ficar de olho

O falante usa 17 contrações e formas reduzidas, como doesn't, we're, you're. Diga-as na forma curta, do jeito que você ouve.

Os sons de “th”: threshold /ˈθɹɛʃ(h)oʊld/, mathematics /mæθ(.ə)ˈmæt.ɪks/
Os sons de “sh” e “zh”: threshold /ˈθɹɛʃ(h)oʊld/, unusual /ʌnˈjuːʒ(u)əl/, efficient /ɪˈfɪʃənt/, instruction /ɪnˈstɹʌkʃən/, calibration /ˌkæl.ɪˈbɹeɪ.ʃən/
Palavras longas — acerte a sílaba tônica: probability /ˌpɹɑ.bəˈbɪl.ə.ti/, automatic /ˌɔː.təˈmæt.ɪk/, mathematics /mæθ(.ə)ˈmæt.ɪks/, necessarily /ˌnɛs.əˈsɛɹ.ə.li/, unusual /ʌnˈjuːʒ(u)əl/

Como praticar com este vídeo

Ouça o vídeo inteiro uma vez sem falar e anote as palavras que você não conhece.
Faça shadowing frase por frase na velocidade normal, repetindo cada uma até o seu ritmo ficar igual ao do falante.
Grave a sua voz e compare com o original, prestando atenção a palavras como probability, refund, reward.

O que é a Técnica de Shadowing?

Shadowing é uma técnica de aprendizado de idiomas com base científica, originalmente desenvolvida para o treinamento de intérpretes profissionais. O método é simples, mas poderoso: você ouve áudio em inglês nativo e repete imediatamente em voz alta — como uma sombra seguindo o falante com 1-2 segundos de atraso. Pesquisas mostram melhora significativa na precisão da pronúncia, entonação, ritmo, sons conectados, compreensão auditiva e fluência na fala.

Técnica de shadowing: leia o guia completo passo a passo →

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Vocabulário e dicas de fala para esta lição

Vocabulário principal deste vídeo

Phrasal verbs que você vai ouvir

Gramática neste vídeo

Pronúncia para ficar de olho

Como praticar com este vídeo

O que é a Técnica de Shadowing?