Dirk Wulff | Max Planck Institute for Human Development (original) (raw)

Papers by Dirk Wulff

How does the mental lexicon, the network of learned words in our semantic memory, change in old a... more How does the mental lexicon, the network of learned words in our semantic memory, change in old age? To address this question, we employ a new network inference method to infer networks from verbal fluency data of a group of younger and older adults. We find that older adults produce more unique words in verbal fluency tasks than younger adults. In line with recent theorizing, this suggests a larger mental lexicon for older than for younger adults. Moreover, we find that relative to the mental lexicon of younger adults, the mental lexicon of older adults is less small-world-like. Based on several findings linking network clustering to processing speed, this finding suggests that not only the size, but also the structure of the mental lexicon may contribute to apparent cognitive decline in old age.

In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting mode... more In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting models with a set of heuristic models of intertemporal choice using a cross-validation approach. Consistent with earlier reports, Ericsson and colleagues concluded that heuristic models (specifically their novel intertemporal choice heuristic or ITCH model) explain intertemporal choices better than discounting models do. More surprisingly, their results showed that all discounting models performed nearly at chance level, and did not outperform even the baseline model. In this article, however, we demonstrate that these conclusions are premature. Specifically, we reanalyzed the Ericson et al. (2015) data under different, arguably more appropriate, conditions and found that models of both classes are rather good at predicting choice. We conclude that the jury is still out on which (type of) model is best and end by making suggestions towards conducting more informative model comparisons.

In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting mode... more In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting models with a set of heuristic models of intertemporal choice using a cross-validation approach. Consistent with earlier reports, Ericsson and colleagues concluded that heuristic models (specifically their novel intertemporal choice heuristic or ITCH model) explain intertemporal choices better than discounting models do. More surprisingly, their results showed that all discounting models performed nearly at chance level, and did not outperform even the baseline model. In this article, however, we demonstrate that these conclusions are premature. Specifically, we reanalyzed the Ericson et al. (2015) data under different, arguably more appropriate, conditions and found that models of both classes are rather good at predicting choice. We conclude that the jury is still out on which (type of) model is best and end by making suggestions towards conducting more informative model comparisons.

To what extent do people adapt their information search policies and subsequent decisions to the ... more To what extent do people adapt their information search policies and subsequent decisions to the long-and short-run consequences of choice environments? To address this question, we investigated exploration and exploitation policies in choice environments that involved single or multiple plays. We further compared behavior in these environments with behavior in the standard sampling paradigm. Frequently used in research on decision from experience, this paradigm does not explicitly implement the choice in terms of the short or long run. Results showed that people searched more in the multi-play environment than in the single-play environment. Moreover, the substantial search effort in the multi-play environment was conducive to choices consistent with expected value maximization, whereas the lesser search effort in the single-play environment was compatible with the goal of maximizing the chance of winning something. Furthermore, choice and search behaviors in the sampling paradigm predominantly echoed those observed in the single-play environment. This suggests that, when not instructed otherwise, participants in the sampling paradigm appear to favor search and choice strategies that embody short-run aspirations. Finally, the present findings challenge the revealed preference approach in decisions from experience, while also suggesting that information search may be an important and potentially even better signal of preference or aspirations than choice.

Modeling Valuations From Experience: A Comment on Ashby and Rakow (2014)

What are the cognitive mechanisms underlying subjective valuations formed on the basis of sequent... more What are the cognitive mechanisms underlying subjective valuations formed on the basis of sequential experiences of an option's possible outcomes? Ashby and Rakow (2014) have proposed a sliding window model (SWIM), according to which people's valuations represent the average of a limited sample of recent experiences (the size of which is estimated by the model) formed after sampling has been terminated (i.e., an end-of-sequence process). Ashby and Rakow presented results from which they concluded, on the basis of model-selection criteria, that the SWIM performs well compared with alternative models (e.g., value-updating model, summary model). Further, they reported that the individual window sizes estimated by the SWIM correlated with a measure of working-memory capacity. In a reanalysis of the Ashby and Rakow data, we find no clear evidence in support of any of the models tested, and a slight advantage for the summary model. Further, we demonstrate that individual differences in the window-size estimated by the SWIM can reflect differences in noise. In computer simulations, we examine the more general question of how well the models tested by Ashby and Rakow can actually be discriminated. The results reveal that the models' ability to fit data depends on a complex interplay of noise and the sample size of outcomes on which a valuation response is based. This can critically influence model performance and conclusions regarding the underlying cognitive mechanisms. We discuss the implications of these findings and suggest ways of improving model comparisons in valuations from experience.

The analogy of space to human cognition has a long- standing tradition. Our study aims to elabora... more The analogy of space to human cognition has a long- standing tradition. Our study aims to elaborate on the validity of this analogy for search in memory. Using the search of associative memory framework (SAM) we show that people are able to dynamically recruit independent memory representations in the recall of country names. By instructing participants to use specific recall cues we also show that despite a strong effect on the retrieval sequence, total recall from memory remains unaffected. Whereas these findings strongly support a higher dimensionality to memory than often assumed, the simultaneous finding of severe retrieval time costs for non-default representations suggests that the use of particular retrieval structures may be adaptive. In sum, our results support local-to-global memory search strategies similar to foraging strategies in space, but further suggest that memory is not constrained to one local representation, but may indeed support many.

For over 50 years expected value and expected utility theory has been challenged by behavioral fi... more For over 50 years expected value and expected utility theory has been challenged by behavioral findings in repeated and single plays of risky gambles. The inherent long-term nature of these models has been found to be at odds with preferences indicating short-term maximization in single play situations. With the present study we provide further evidence on the distinction between long-term and short-term oriented behavior. Evaluating experienced- based decisions over repeated and single play situations we demonstrate that both choice preferences and search behavior change in response to long and short-term framing. This suggests different cognitive approaches for single and repeated play situations, with single decisions often favoring risk-aversion and therefore the underweighting of rare events. These findings are in line with alternative models of risky choice as for example proposed by Lopes (1996) and also the literature on state- dependent foraging.

People can access information about choices in at least two ways: via summary descriptions that p... more People can access information about choices in at least two ways: via summary descriptions that provide an overview of potential outcomes and their likelihood of occurrence or via sequential presentation of outcomes. Provided with the former, people make decisions from description; with the latter, they make decisions from experience. Recent investigations involving risky choices have demonstrated a robust and systematic description–experience gap. Specifically, when people make decisions from experience, rare events tend to have less impact than what they deserve according to their objective probability. Here, we show that this description–experience gap generalizes from choices involving monetary gambles to choices based on (hypothetical) online product ratings. We further show that causes that have been identified in the context of risky choice also contribute to the description–experience gap in choice based on online product ratings: reliance on relatively small samples of information and overweighting of recently sampled information (recency). We conclude with a discussion of the practical implications of our results and identify promising directions for cross-disciplinary investigations.

How does the mental lexicon, the network of learned words in our semantic memory, change in old a... more How does the mental lexicon, the network of learned words in our semantic memory, change in old age? To address this question, we employ a new network inference method to infer networks from verbal fluency data of a group of younger and older adults. We find that older adults produce more unique words in verbal fluency tasks than younger adults. In line with recent theorizing, this suggests a larger mental lexicon for older than for younger adults. Moreover, we find that relative to the mental lexicon of younger adults, the mental lexicon of older adults is less small-world-like. Based on several findings linking network clustering to processing speed, this finding suggests that not only the size, but also the structure of the mental lexicon may contribute to apparent cognitive decline in old age.

In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting mode... more In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting models with a set of heuristic models of intertemporal choice using a cross-validation approach. Consistent with earlier reports, Ericsson and colleagues concluded that heuristic models (specifically their novel intertemporal choice heuristic or ITCH model) explain intertemporal choices better than discounting models do. More surprisingly, their results showed that all discounting models performed nearly at chance level, and did not outperform even the baseline model. In this article, however, we demonstrate that these conclusions are premature. Specifically, we reanalyzed the Ericson et al. (2015) data under different, arguably more appropriate, conditions and found that models of both classes are rather good at predicting choice. We conclude that the jury is still out on which (type of) model is best and end by making suggestions towards conducting more informative model comparisons.

In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting mode... more In a recent article, Ericsson and colleagues (2015) compared traditional utility-discounting models with a set of heuristic models of intertemporal choice using a cross-validation approach. Consistent with earlier reports, Ericsson and colleagues concluded that heuristic models (specifically their novel intertemporal choice heuristic or ITCH model) explain intertemporal choices better than discounting models do. More surprisingly, their results showed that all discounting models performed nearly at chance level, and did not outperform even the baseline model. In this article, however, we demonstrate that these conclusions are premature. Specifically, we reanalyzed the Ericson et al. (2015) data under different, arguably more appropriate, conditions and found that models of both classes are rather good at predicting choice. We conclude that the jury is still out on which (type of) model is best and end by making suggestions towards conducting more informative model comparisons.

To what extent do people adapt their information search policies and subsequent decisions to the ... more To what extent do people adapt their information search policies and subsequent decisions to the long-and short-run consequences of choice environments? To address this question, we investigated exploration and exploitation policies in choice environments that involved single or multiple plays. We further compared behavior in these environments with behavior in the standard sampling paradigm. Frequently used in research on decision from experience, this paradigm does not explicitly implement the choice in terms of the short or long run. Results showed that people searched more in the multi-play environment than in the single-play environment. Moreover, the substantial search effort in the multi-play environment was conducive to choices consistent with expected value maximization, whereas the lesser search effort in the single-play environment was compatible with the goal of maximizing the chance of winning something. Furthermore, choice and search behaviors in the sampling paradigm predominantly echoed those observed in the single-play environment. This suggests that, when not instructed otherwise, participants in the sampling paradigm appear to favor search and choice strategies that embody short-run aspirations. Finally, the present findings challenge the revealed preference approach in decisions from experience, while also suggesting that information search may be an important and potentially even better signal of preference or aspirations than choice.

Modeling Valuations From Experience: A Comment on Ashby and Rakow (2014)

What are the cognitive mechanisms underlying subjective valuations formed on the basis of sequent... more What are the cognitive mechanisms underlying subjective valuations formed on the basis of sequential experiences of an option's possible outcomes? Ashby and Rakow (2014) have proposed a sliding window model (SWIM), according to which people's valuations represent the average of a limited sample of recent experiences (the size of which is estimated by the model) formed after sampling has been terminated (i.e., an end-of-sequence process). Ashby and Rakow presented results from which they concluded, on the basis of model-selection criteria, that the SWIM performs well compared with alternative models (e.g., value-updating model, summary model). Further, they reported that the individual window sizes estimated by the SWIM correlated with a measure of working-memory capacity. In a reanalysis of the Ashby and Rakow data, we find no clear evidence in support of any of the models tested, and a slight advantage for the summary model. Further, we demonstrate that individual differences in the window-size estimated by the SWIM can reflect differences in noise. In computer simulations, we examine the more general question of how well the models tested by Ashby and Rakow can actually be discriminated. The results reveal that the models' ability to fit data depends on a complex interplay of noise and the sample size of outcomes on which a valuation response is based. This can critically influence model performance and conclusions regarding the underlying cognitive mechanisms. We discuss the implications of these findings and suggest ways of improving model comparisons in valuations from experience.

The analogy of space to human cognition has a long- standing tradition. Our study aims to elabora... more The analogy of space to human cognition has a long- standing tradition. Our study aims to elaborate on the validity of this analogy for search in memory. Using the search of associative memory framework (SAM) we show that people are able to dynamically recruit independent memory representations in the recall of country names. By instructing participants to use specific recall cues we also show that despite a strong effect on the retrieval sequence, total recall from memory remains unaffected. Whereas these findings strongly support a higher dimensionality to memory than often assumed, the simultaneous finding of severe retrieval time costs for non-default representations suggests that the use of particular retrieval structures may be adaptive. In sum, our results support local-to-global memory search strategies similar to foraging strategies in space, but further suggest that memory is not constrained to one local representation, but may indeed support many.

For over 50 years expected value and expected utility theory has been challenged by behavioral fi... more For over 50 years expected value and expected utility theory has been challenged by behavioral findings in repeated and single plays of risky gambles. The inherent long-term nature of these models has been found to be at odds with preferences indicating short-term maximization in single play situations. With the present study we provide further evidence on the distinction between long-term and short-term oriented behavior. Evaluating experienced- based decisions over repeated and single play situations we demonstrate that both choice preferences and search behavior change in response to long and short-term framing. This suggests different cognitive approaches for single and repeated play situations, with single decisions often favoring risk-aversion and therefore the underweighting of rare events. These findings are in line with alternative models of risky choice as for example proposed by Lopes (1996) and also the literature on state- dependent foraging.

People can access information about choices in at least two ways: via summary descriptions that p... more People can access information about choices in at least two ways: via summary descriptions that provide an overview of potential outcomes and their likelihood of occurrence or via sequential presentation of outcomes. Provided with the former, people make decisions from description; with the latter, they make decisions from experience. Recent investigations involving risky choices have demonstrated a robust and systematic description–experience gap. Specifically, when people make decisions from experience, rare events tend to have less impact than what they deserve according to their objective probability. Here, we show that this description–experience gap generalizes from choices involving monetary gambles to choices based on (hypothetical) online product ratings. We further show that causes that have been identified in the context of risky choice also contribute to the description–experience gap in choice based on online product ratings: reliance on relatively small samples of information and overweighting of recently sampled information (recency). We conclude with a discussion of the practical implications of our results and identify promising directions for cross-disciplinary investigations.