Search PubMed⌕ Search

Biomedical subjects

Koen Lamberts

Publications and source records attributed to Koen Lamberts.

10 recordsLinked to original sources
PubMed2006

The time course of perception and retrieval in matching and recognition.

A four-part experiment was carried out to study the relationship between the time course of object-feature perception and the time course of retrieval of object information from memory. The experiment consisted of 2 perceptual matching tasks, and 2 perceptual recognition tasks. In all 4 tasks, participants provided speeded judgments of the identity of 2 objects. A stochastic feature-sampling model was used to estimate the time needed for feature perception and the time needed for retrieval of feature information. No evidence was found for a systematic relationship between perception times and retrieval times for individual features. Indeed, the model applications indicated that retrieval times were constant for different features, whereas perception rates varied across the features.

Adolescent↗
PubMed2006

Perceptual similarity in autism.

People with autism have consistently been found to outperform controls on visuo-spatial tasks such as block design, embedded figures, and visual search tasks. Plaisted, O'Riordan, and others (Bonnel et al., 2003; O'Riordan & Plaisted, 2001; O'Riordan, Plaisted, Driver, & Baron-Cohen, 2001; Plaisted, O'Riordan, & Baron-Cohen, 1998a, 1998b) have suggested that these findings might be explained in terms of reduced perceptual similarity in autism, and that reduced perceptual similarity could also account for the difficulties that people with autism have in making generalizations to novel situations. In this study, high-functioning adults with autism and ability-matched controls performed a low-level categorization task designed to examine perceptual similarity. Results were analysed using standard statistical techniques and modelled using a quantitative model of categorization. This analysis revealed that participants with autism required reliably longer to learn the category structure than did the control group but, contrary to the predictions of the reduced perceptual similarity hypothesis, no evidence was found of more accurate performance by the participants with autism during the generalization stage. Our results suggest that when all participants are attending to the same attributes of an object in the visual domain, people with autism will not display signs of enhanced perceptual similarity.

Adult↗
PubMed2005

Interpretation of orthographic uniqueness point effects in visual word recognition.

The orthographic uniqueness point (OUP) of a word is the position of the first letter from the left that distinguishes a word from all other words. In 2 recent studies (P. J. Kwantes & D. J. K. Mewhort, 1999a; A. K. Lindell, M. E. R. Nicholls, & A. E. Castles, 2003), it has been observed that words with an early OUP were processed more quickly than words with a late OUP. This has been taken to suggest that observers process the letters of words sequentially in a left-to-right order. In this article, it is shown that the OUP results do not provide selective evidence for left-to-right sequential processing in visual word recognition because the data are also compatible with an account in which letter processing occurs in random order.

Attention↗
PubMed2005

An exemplar account of the bow and set-size effects in absolute identification.

The extended generalized context model for response times (K. Lamberts, 2000) was designed to account for choice proportions and response times in perceptual categorization. In this article, the hypothesis that the model also offers an account of accuracy and response times in absolute identification was investigated. The model was applied to the data from 2 absolute identification experiments and provided a good account of the bow and the set-size effects in accuracy and response time data from individual participants, including the response time distributions for individual stimuli. The model applications demonstrated that exemplar-based process models offer a viable account of absolute identification data.

Adult↗
PubMed2004

Strategic processes in false recognition memory.

In two experiments, the response signal technique (Reed, 1973) was combined with the DRM paradigm (e.g., McDermott & Roediger, 1998) to investigate the time course of false recognition memory--in particular, how this effect varies along the time course of generating a recognition judgment. Across the experiments, in addition to standard instructions, there were forewarning instructions encouraging the participants to avoid this effect, as well as inclusion instructions intended to enhance this tendency. It was found that the false memory effect was at its strongest at earlier response signals, diminishing when more time was given to make a recognition judgment. The forewarning instructions led to a more conservative overall response bias, rather than to a reduction of the effect. However, the participants were able to exaggerate this effect in the inclusion condition. The results are discussed in terms of the role of strategic processing in recognition memory.

Humans↗
PubMed2003

Feature-sampling and random-walk models of individual-stimulus recognition.

Traditional process models of old-new recognition have not addressed differences in accuracy and response time between individual stimuli. Two new process models of recognition are presented and applied to response time and accuracy data from 3 old-new recognition experiments. The 1st model is derived from a feature-sampling account of the time course of categorization, whereas the 2nd model is a generalization of a random-walk model of categorization. In the experiments, a new technique was used, which yielded reliable individual-stimulus data through repeated presentation of structurally equivalent items. The results from the experiments showed reliable differences in accuracy and response times between stimuli. The random-walk model provided the better account of the results from the 3 experiments. The implications of the results for process models of recognition are discussed.

Adult↗
PubMed2003

Adaptive changes of response criterion in recognition memory.

An experiment was conducted to investigate people's ability to vary a response criterion strategically, in a recognition memory task, as a function of the length of time given to process the test stimuli (from 100 to 1,500 msec). The experiment used the response signal procedure, in which the participants responded after a signal that came at a variable time delay from stimulus onset. The proportion of new versus old test items was varied systematically with the time of the response signal, with the proportion of new test items rising, falling, or staying constant at later signals. It was found that the participants' response biases changed adaptively, becoming more conservative at later signals in the rising condition, becoming less conservative in the falling condition, and not changing significantly in the constant condition. Theoretical and methodological implications for recognition memory research are discussed.

Adaptation, Psychological↗
PubMed2002

Feature sampling in categorization and recognition of objects.

This article presents an overview of some recent work on the time course of perceptual categorization and recognition memory. First, The EGCM-RT, which is a feature-sampling model of the time course of categorization, is described. It is shown that the model explains a wide range of categorization data. Second, an overview is given of a feature-sampling model of the time course of recognition that is derived from the EGCM-RT. This model explains results that have been interpreted in the past as evidence for dual-process models of recognition, and it provides a single-process alternative to dual-process accounts.

Humans↗
PubMed2002

Perceptual processes in matching and recognition of complex pictures.

The role of perceptual feature sampling in speeded matching and recognition was explored in 4 experiments. Experiments 1-3 involved a perceptual matching task with pictures of various objects and scenes. In Experiments 2 and 3, same-different judgments were given under time pressure. The main objective of the matching task was to obtain measures of the perceptual processing rates of different object features. Experiment 4 was an old-new recognition experiment, in which the same stimuli as those in the matching task were used. Response signals were used to limit processing time in the recognition task. The results demonstrated that it is possible to predict speeded recognition performance from performance in perceptual matching. A simple stochastic feature-sampling model provides a unified account of the data from the 4 experiments.

Analysis of Variance↗