# Implicit serial learning in monkeys and humans

> **NIH NIH R01** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2021 · $507,970

## Abstract

Project Summary
One of the oldest questions in psychology and neuroscience is whether associations of stimuli and responses
are sufficient to explain learning. Or, in addition, are there conditions that require knowledge of rules and
representations? We propose a new approach to the study of serial learning by investigating how humans and
monkeys infer ordinal knowledge implicitly during training on a Transitive Inference (TI) task. In its simplest
form, TI is the ability to conclude that A > C, if A > B and B > C, but here we extend the same logic to longer
series composed of 7 items. TI has been shown to exist in species as diverse as pigeons, monkeys, and
humans and has been used to explain complex social relationships such as dominance hierarchies. TI is
critical for understanding ordinal knowledge, which, by definition, obeys transitivity, and which is believed to
give rise to an internal representation of serial order. To investigate this theory, we plan to study learning and
representation of ordinal knowledge during and following TI training in monkeys and human subjects. The logic
of our experiments is to show (1) how manipulations of expected value do not alter the representation of
ordinal knowledge in studies on overtraining of particular pairs during TI acquisition and in studies in which
there is a reversal of reward magnitude during TI training, (2) overtraining of a particular stimulus-response
contingency does not impair learning, and (3) the inability of association theory to account for accurate
performance on derived lists on which knowledge of associations learned on the original list are irrelevant. Our
monkey experiments are the first to investigate implicit inference at the behavioral level that is synchronized to
simultaneous measurement of the activity of individual neurons in prefrontal cortex (PFC) and posterior parietal
cortex (PPC) throughout TI learning (including acquisition). Our experiments aim to show that 1) TI training
leads to a representation of serial order of novel stimulus pairs and 2) ordinal position and symbolic distance
are represented in PFC and LIP and that those representations arise de novo each time an animal learns a
new list. Health Relatedness: These experiments are relevant to Schizophrenia, Autism, Alzheimer’s disease,
and other conditions whose patient populations have deficits in learning and reasoning that manifest in the
performance of TI problems.

## Key facts

- **NIH application ID:** 10145787
- **Project number:** 5R01MH111703-04
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** VINCENT P FERRERA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $507,970
- **Award type:** 5
- **Project period:** 2018-07-05 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10145787

## Citation

> US National Institutes of Health, RePORTER application 10145787, Implicit serial learning in monkeys and humans (5R01MH111703-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10145787. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*