Philip T. Quinlan

Cascade processes in picture identification

Abstract The naming of pictures is typically thought to require sequential access to stored structural knowledge about objects, to semantic knowledge, and to a stored phonological description. Access to these different types of knowledge may constitute discrete processing stages; alternatively, it may be that information is transmitted continuously (in cascade) from one type of description to the next. The discrete stage and the cascade accounts make different predictions about the effects of structural and semantic similarity between objects on picture naming. The discrete stage account maintains that the effects of structural similarity should be confined to the process of accessing an objects structural description, and the effects of semantic similarity should be confined to the process of accessing semantic knowledge. The cascade account predicts that the effect of both variables may be passed on to subsequent processing stages. We present evidence drawn from both normal observers and from a patient...

Age of acquisition, not word frequency, affects object naming, not object recognition

Word frequency is widely believed to affect object naming speed, despite several studies in which it has been reported that frequency effects may be redundant upon age of acquisition. We report, first, a reanalysis of data from the study by Oldfield and Wingfield (1965), which is standardly cited as evidence for a word frequency effect in object naming; then we report two new experiments. The reanalysis of Oldfield and Wingfield shows that age of acquisition is the major determinant of naming speed, and that frequency plays no independent role when its-correlation with other variables is taken into account. In Experiment 1, age of acquisition and phoneme length proved to be the primary determinants of object naming speed. Frequency, prototypicality, and imageability had no independent effect. In Experiment 2, subjects classified objects into two semantic categories (natural or man-made). Prototypicality and semantic category were the only variables to have a significant effect on reaction time, with no effect of age of acquisition, frequency, imageability, or word length. We conclude that age of acquisition, not word frequency, affects the retrieval andlor execution of object names, not the process of object recognition. The locus of this effect is discussed, along with the possibility that words learned in early childhood may be more resistant to the effects of brain injury in at least some adult aphasics than words learned somewhat later.

Orthographic processing in visual word identification

A series of experiments is reported examining orthographic priming effects between briefly presented pairs of letter strings. The experiments investigate the effects of the number and position of letters shared by primes and targets, and the effects of prime-target length. Priming effects increase nonlinearly as a function of both the number and the position of shared letters, and they are dependent on the positions of letters relative to both the end positions in the string and to the identities of their nearest neighbours. There is little effect of absolute string length on priming. These priming effects can be distinguished from intrusion errors where letters from primes are reported in response to targets. An account of orthographic processing is outlined which attributes priming to cooperative interactions between coarse relative-position coded letter cluster representations activated by primes and targets. The implications of the findings for understanding other effects in word recognition and reading are discussed.

Visual search for targets defined by combinations of color, shape, and size: An examination of the task constraints on feature and conjunction searches

A series of experiments are reported in which the comparative constraints on single-feature and conjunction searches were examined. The first three tested the idea that the critical differences between these searches reflect the number of stimulus attributes that subjects must extract to make a response, that is, one in the feature condition, two in the conjunction condition. Targets were defined by possible pairwise combinations of a color, a size, and a shape. In another condition, subjects searched for two simultaneously present feature targets. Search for these targets did not differ qualitatively from that for a single-feature target (i.e., search remained parallel), but there was a constant increment to feature search functions. The final experiment examined the possibility that the number of relevant shared features between targets and distractors may also be critical. The results showed that the number of relevant shared features affected the rate of search but not its nature. Thus, differences between feature and conjunction searches do not reflect the number of relevant stimulus attributes that must be detected, or the number of relevant features shared between targets and distractors. Nevertheless, evidence for attentional involvement was found when subjects searched for two simultaneously present features. This goes against the claim that differences between the two types of search occur because feature searches can be carried out preattentively, while only conjunction searches involve the serial application of focused attention. An account of visual search performance that emphasizes the fidelity of coding of target information seems a more adequate proposal.

Searching for threat.

In a series of experiments, a visual search task was used to test the idea that biologically relevant threatening stimuli might be recognized very quickly or capture visuo-spatial attention. In Experiment 1, there was evidence for both faster detection and faster search rates for threatening animals than for plants. However, examination of the basis of this effect in Experiment 2 showed that it was not due to threat per se, as detection and search rate advantages were found for pleasant rather than threatening animals compared to plants. In Experiment 3, participants searched for the plants and pleasant and threatening animals used in Experiments 1 and 2, among a fixed heterogeneous selection of non-target items. There was no search rate or detection advantage for threatening animals compared to pleasant animals or plants. The same targets and non-targets as those used in Experiment 3 were also used in Experiment 4. In Experiment 4, participants searched for targets that were presented either close to or distant from an initial fixation point. There was no evidence for a “threat” detection advantage either close to or distant from the cross. Finally, an experiment was conducted in which target categories (fruit, flowers, and animals) were not pre-specified prior to each trial block. There were no differences in reaction times to detect pleasant animals, threatening animals, or fruit. We conclude that the visual search paradigm does not readily reveal any biases that might exist for threatening stimuli in the general population.

Visual feature integration theory: Past, present, and future

Visual feature integration theory was one of the most influential theories of visual information processing in the last quarter of the 20th century. This article provides an exposition of the theory and a review of the associated data. In the past much emphasis has been placed on how the theory explains performance in various visual search tasks. The relevant literature is discussed and alternative accounts are described. Amendments to the theory are also set out. Many other issues concerning internal processes and representations implicated by the theory are reviewed. The article closes with a synopsis of what has been learned from consideration of the theory, and it is concluded that some of the issues may remain intractable unless appropriate neuroscientific investigations are carried out.

Grouping by Proximity or Similarity? Competition between the Gestalt Principles in Vision

The nature of the psychological processes that underlie the Gestalt principles of grouping by proximity and grouping by similarity is examined. Similarity was defined relative to the principles of grouping by common colour and grouping by common shape. Subjects were presented with displays comprising a row of seven coloured shapes and were asked to rate the degree to which the central target shape grouped with either the right or the left flanking shapes. Across the displays the proximal and featural relationships between the target and flankers were varied. These ratings reflected persuasive effects of grouping by proximity and common colour; there was only weak evidence for grouping by common shape. Nevertheless, both common colour and common shape were shown to override grouping by proximity, under certain conditions. The data also show that to understand how the Gestalt principles operate it appears necessary to consider processes that operate within and between groups of elements that are initially identified on the basis of proximity. Whether such groups survive further analysis depends critically on the featural content of the constituent elements.

Garner and Congruence Effects in the Speeded Classification of Bimodal Signals

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli.

The effects of stimulus set size and word frequency on verbal serial recall.

Two experiments are reported which examine immediate serial recall for high-and low-frequency words. The words in each list were either repeatedly drawn from the same small pool of candidates (in the closed set conditions) or each word only ever occurred once during the experiment (in the open set conditions). The results consistently show an effect of word frequency but the effect of set size was only apparent for low-frequency words. It is argued that both frequency and set size effects reflect processes concerning the “clean-up” of degraded short-term memory traces.

Frequency effects in spoken and visual word recognition: evidence from dual-task methodologies.

The authors report 3 dual-task experiments concerning the locus of frequency effects in word recognition. In all experiments, Task 1 entailed a simple perceptual choice and Task 2 involved lexical decision. In Experiment 1, an underadditive effect of word frequency arose for spoken words. Experiment 2 also showed underadditivity for visual lexical decision. It was concluded that word frequency exerts an influence prior to any dual-task bottleneck. A related finding in similar dual-task experiments is Task 2 response postponement at short stimulus onset asynchronies. This was explored in Experiment 3, and it was shown that response postponement was equivalent for both spoken and visual word recognition. These results imply that frequency-sensitive processes operate early and automatically.