Date of Award


Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy (PhD)


Developmental and Brain Sciences

First Advisor

Zsuzsa Kaldy

Second Advisor

Erik Blaser

Third Advisor

Susan Zup


Imagine you are cooking and the recipe calls for 1⁄3 cup of flour and 1⁄2 cup of sugar. When you go to retrieve these items you might accidentally add 1⁄2 cup of flour. This is due to a phenomenon called Proactive Interference (PI), when during retrieval, previously relevant information competes with currently relevant information, resulting in errors and/or slower responses (Badre & Wagner, 2007; Bunge & Wright, 2007; O’Reilly & Frank, 2006). PI has been postulated as a main cause of limitations in WM, (Anderson & Neely, 1996; Bunting, 2006; Endress & Potter, 2014; Kane & Engle, 2000) a limited capacity system responsible for the activation and manipulation of items in order to solve a task (Baddeley, 1992). The limitations of this system are a central interest in the field because this is in stark contrast with long term memory that has no known limitations. WM is required for a large number of important cognitive abilities such as mental math, playing chess or doing puzzles. Thus, understanding these limitations has important real-world implications.

In a series of experiments, using a delayed match retrieval paradigm (Kaldy et al., 2016), I ask whether young children (between the ages of 18 months and 7.5 years) are sensitive to PI and whether the ability to inhibit proactive interference strengthens across development.

In the adult literature PI is a well-established phenomenon (Endress & Potter, 2014; Kane & Engle, 2000; Oberauer et al., 2016). Traditionally, this was measured with auditory stimuli (Keppel & Underwood, 1962). Adults were asked to memorize items from a series of lists and performance decreased as trials progressed. It has since been established in visual WM (Endress & Potter, 2014; Hartshorne, 2008; Makovski & Jiang, 2008), although how robust these effects might be is a subject of debate (Lin & Luck, 2012). But to date, no one has systematically studied PI in children younger than 4 years old. Thus, in a series of experiments I investigate the magnitude (and the source) of the PI effect in children between the ages of 18 months and 7.5 years.

In Chapter 1, I review the extensive research looking at PI resolution abilities in adults. I then identify a major gap in the literature and suggest that more research is needed to understand how PI is treated in early childhood. In adults, neural mechanisms in prefrontal regions (particularly the left inferior frontal gyrus and posterior parietal cortex) are activated when inhibiting irrelevant information. Thus, we hypothesize that inhibiting PI becomes easier because of a strengthening of neural networks in the prefrontal regions that are not yet fully developed in childhood.

Although few papers investigated the resolution of PI in children, there is some research that suggests that as age increases so does the ability to resolve PI. For example,Kail (2002) conducted a meta-analysis that showed that children become better at inhibiting the effects of PI from age 4 into adulthood. This meta-analysis was not conducted using studies that directly studied PI. Instead, he analyzed studies that investigated memory in young children and found that performance decreased across trials. But no paper to date has investigated this in children under 4 years of age. Thus, in Chapter 2, I investigate three main questions. 1) 3-year-old children are, in fact, highly sensitive to the effects of PI. 2) Interfering information stems from reactivated information from long(er) term memory and from not information that is lingering in WM from previous trials. 3) PI resolution abilities improve across early childhood.

In Chapter 3, I investigate how even younger children (18 to 30 months) resolve PI. In order to follow open science practices for rigor and reproducibility, all studies reported in Chapter 2 and 3 were preregistered on Open Science Framework and all stimuli, code and results are openly available as well.

Thus, I establish, in the youngest age to date, that younger children have more difficulty inhibiting the effects of PI than older children and my data suggests that this ability progresses over early childhood. This could have important information regarding the mechanisms underlying WM. In addition to the theoretical implications, there are important methodological implications as well. Traditionally, WM capacity has been studied in infants and young children by presenting them with a series of repeating identical or similar stimuli hence, inducing PI, which might vastly underestimate WM capacity to date.


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