The effects of graphemic and phonemic similarity between targets and masks in a backward visual masking paradigm

Experiments using a backward visual masking technique are described, in which the second (mask) stimulus is itself masked by a third stimulus, thus rendering guessing strategies, about target/mask relationships, difficult for subjects. Word-word and word-non-word sequences are used for the first two stimuli and it is shown that when the second stimulus resembles the first, either physically or phonologically, the severity of masking of the first is reduced. However, the target is not better reported when the mask word is semantically related to it. Consideration is given to the levels at which interaction between target and mask might occur.     

A stimulus set of words and pictures matched for visual and semantic similarity

Researchers in different fields of psychology have been interested in how vision and language interact, and what type of representations are involved in such interactions. We introduce a stimulus set that facilitates such research (available online). The set consists of 100 words each of which is paired with four pictures of objects: One semantically similar object (but visually dissimilar), one visually similar object (but semantically dissimilar), and two unrelated objects. Visual and semantic similarity ratings between corresponding items are provided for every picture for Dutch and for English. In addition, visual and linguistic parameters of each picture are reported. We thus present a stimulus set from which researchers can select, on the basis of various parameters, the items most optimal for their research question.     

The effect of visual and acoustic similarity on short-term memory for chinese words

Four lists of Chinese words in a 2 × 2 factorial design of visual and acoustic similarity were used in a short-term memory experiment. In addition to a strong acoustic similarity effect, a highly significant visual similarity effect was also obtained. This was particularly pronounced in the absence of acoustic similarity in the words used. The results not only confirm acoustic encoding to be a basic process in short-term recall of verbal stimuli in a language other than English but also lend support to the growing evidence of visual encoding in short-term memory as the situation demands.     

Effects of targets embedded within words in a visual search task

Visual search performance can be negatively affected when both targets and distracters share a dimension relevant to the task. This study examined if visual search performance would be influenced by distracters that affect a dimension irrelevant from the task. In Experiment 1 within the letter string of a letter search task, target letters were embedded within a word. Experiment 2 compared targets embedded in words to targets embedded in nonwords. Experiment 3 compared targets embedded in words to a condition in which a word was present in a letter string, but the target letter, although in the letter string, was not embedded within the word. The results showed that visual search performance was negatively affected when a target appeared within a high frequency word. These results suggest that the interaction and effectiveness of distracters is not merely dependent upon common features of the target and distracters, but can be affected by word frequency (a dimension not related to the task demands).     

Object-based auditory facilitation of visual search for pictures and words with frequent and rare targets

Auditory and visual processes demonstrably enhance each other based on spatial and temporal coincidence. Our recent results on visual search have shown that auditory signals also enhance visual salience of specific objects based on multimodal experience. For example, we tend to see an object (e.g., a cat) and simultaneously hear its characteristic sound (e.g., “meow”), to name an object when we see it, and to vocalize a word when we read it, but we do not tend to see a word (e.g., cat) and simultaneously hear the characteristic sound (e.g., “meow”) of the named object. If auditory–visual enhancements occur based on this pattern of experiential associations, playing a characteristic sound (e.g., “meow”) should facilitate visual search for the corresponding object (e.g., an image of a cat), hearing a name should facilitate visual search for both the corresponding object and corresponding word, but playing a characteristic sound should not facilitate visual search for the name of the corresponding object. Our present and prior results together confirmed these experiential association predictions. We also recently showed that the underlying object-based auditory–visual interactions occur rapidly (within 220 ms) and guide initial saccades towards target objects. If object-based auditory–visual enhancements are automatic and persistent, an interesting application would be to use characteristic sounds to facilitate visual search when targets are rare, such as during baggage screening. Our participants searched for a gun among other objects when a gun was presented on only 10% of the trials. The search time was speeded when a gun sound was played on every trial (primarily on gun-absent trials); importantly, playing gun sounds facilitated both gun-present and gun-absent responses, suggesting that object-based auditory–visual enhancements persistently increase the detectability of guns rather than simply biasing gun-present responses. Thus, object-based auditory–visual interactions that derive from experiential associations rapidly and persistently increase visual salience of corresponding objects.     

Calibrating reach distance to visual targets

The authors investigated the calibration of reach distance by gradually distorting the haptic feedback obtained when participants grasped visible target objects. The authors found that the modified relationship between visually specified distance and reach distance could be captured by a straight-line mapping function. Thus, the relation could be described using 2 parameters: bias and slope. The authors investigated whether calibration generalized across reach space with respect to changes in bias and slope. In Experiment 1, the authors showed that both bias and slope recalibrate. In Experiment 2, they tested the symmetries of reach space with respect to changes in bias. They discovered that reach space is asymmetric, with the bias shifting inward more readily than outward. The authors measured how rapidly the system calibrated and the stability of calibration once feedback was removed. In Experiment 3, they showed that bias and slope can be calibrated independently of one another. In Experiment 4, the authors showed that these calibration effects are not cognitively penetrable.     

Pictures and words in visual search

Ss in three experiments searched through an array of pictures or words for a target item that had been presented as a picture or a word. In Experiments I and II, the pictures were line drawings of familiar objects and the words were their printed labels; in Experiment III, the stimuli were photographs of the faces of famous people and their corresponding printed names. Search times in Experiments I and II were consistently faster when the array items were pictures than when they were words, regardless of the mode of the target items. Search was also faster with pictures than with words as targets when the search array also consisted of pictures, but target mode had no consistent effect with words as array items. Experiment III yielded a completely different pattern of results: Search time with names as targets and faces as search array items was significantly slower than in the other three conditions, which did not differ from each other. Considered in relation to several theories, the results are most consistent with a dual-coding interpretation. That is, items that are cognitively represented both verbally and as nonverbal images can be searched and compared in either mode, depending on the demands of the task. The mode actually used depends on whether the search must be conducted through an array of pictures or words.     

Structural aspects of visual similarity

The hypothesis that visual representations for lines and/or points are independent structural units was tested using similarity judgment and speeded discrimination for pairs of six-segment letter-like figures. The stimuli were constructed such that each of two comparison figures had five segments in common with a standard figure. One figure was similar to the standard in its higher order structure (connectedness and closedness properties), whereas the other differed. The results show that the figures with similar higher order structure were systematically judged more similar to the standard than the figures with different structure. The former were also more difficult to discriminate from standards than the latter, as indicated by both time and error measurements. These effects were less pronounced in sequential than in simultaneous comparisons.     

Differential backward masking of words and letters by masks of varying orthographic structure

The effects of structural relationships between targets and masks were investigated using a backward-masking paradigm. Specifically, the masking of single letters, common fiveletter words, and five-letter pseudowords masked by a blank flash, strings of overlapped letters, pseudowords, and words was investigated. Target duration was varied from 2 to 32 msec, with mask duration held constant at 25 msec. The dependent measure was the critical interstimulus interval for correct target identification. Letters were more effectively masked than words and pseudowords. A blank mask caused the least amount of masking, followed by the overlapped letter strings, and then the word and pseudoword masks. In addition to the overall greater masking effectiveness for the three patterned masks, overlapped letter strings masked letters more effectively than they did words. The implications of current theories of masking for these results and the implications of these results for theories of word recognition were discussed.     

Basic-level visual similarity and category specificity

The role of visual crowding in category deficits has been widely discussed (e.g.,;; ). Most studies have measured overlap at the superordinate level (compare different examples of 'animal') rather than at the basic level (compare different examples of 'dog'). In this study, we therefore derived two measures of basic-level overlap for a range of categories. The first was a computational measure generated by a self-organising neural network trained to process pictures of living and non-living things; the second was a rating of perceived visual similarity generated by human subjects to the item names. The computational measure indicated that the pattern of crowded/uncrowded does not honour a living/non-living distinction. Nevertheless, different superordinates showed varied degrees of basic-level overlap, suggesting that specific token choice affects some superordinates more than others e.g., individual fruit and vegetable tokens show greater variability than any other items, while tools and vehicles produce more reliable or overlapping basic-level visual representations. Finally, subject ratings correlated significantly with the computational measures indicating that the neural model represents structural properties of the objects that are psychologically meaningful.     

Masking effects with targets and nontargets of varying similarity

The relationship between various types of masking, similarity of flanking nontarget shapes to that of a parafoveally presented target character, and target identification accuracy was examined in two experiments. In experiment 1 detection of a gap in a circle or square was more accurate when the target was flanked by two instances of the same shape as the target, but only with energy-limited displays. Pattern masking eliminated the facilitation with identically-shaped flankers and target. In experiment 2 performance was better when a target letter was flanked by letters which were identical in shape to the target or similar in shape (the alternative target) than when the flankers were dissimilar in shape to the target (from a nontarget set). However, performance was best when the target appeared alone, showing a stronger effect of lateral masking than of facilitation. Results were explained with reference to a comparison process which operates only under energy-masking conditions.     

Geometric and semantic similarity in visual masking

Semantic and geometric or physical similarity were manipulated separately in a backward-masking situation. When the target was a word to be read aloud, formal similarity between the letters of target and mask facilitated target recognition, as did associative similarity. Masking a target word by its own anagram also facilitated whole word report. In contrast, formal similarity was inhibitory rather than facilitatory of report when the target was spelled letter-by-letter, rather than read whole. This was true even for the same target words whose whole report was facilitated by formal similarity. A model to account for this reversal in the broader context of the neural substrate of reading is advanced. It is proposed that letter and word processing are fundamentally different in that letters are recognized by hierarchical feature analysis while words are stored and recognized wholistically by diffuse and redundant networks. Implications of the results for the study of reading are discussed.     

Familiarity affects visual processing of words.

While previous research has demonstrated that words can be processed more rapidly and/or more accurately than random strings of letters, it has not been convincingly demonstrated that the superior processing of words is a visual effect. In the present experiment, the cases of letters were manipulated in letter strings that were to be compared on the basis of physical identity. Mean response time was shorter for words than for nonwords even for pairs of letter strings that differed only in case (e.g., site-site). This finding implies that the advantage of words over nonwords (the familiarity effect) typically observed in the simultaneous matching task is not due solely to comparison of either the word names or the letter names and, thus, that at least part of the familiarity effect must be due to more rapid formation and/or comparison of visual representations of the two letter strings when they are words. Further analysis failed to reveal a significant involvement of phonemic or lexical codes in the comparison judgments.     

Helmets improve estimations of depth and visual angle to safe targets

Egocentric distance estimation has been shown to depend on wearing safety gear, which promotes compensatory behavior, and on target type, which regulates fight-or-flight responses. We hypothesized that the two factors interact, possibly in asymmetric fashion, and set out to uncover the limits of this interaction in a perceptual task where individuals wearing helmets or baseball caps estimated egocentric distance to non-threatening and threatening animals depicted on cards (i.e., safe and unsafe targets). We found that, compared to participants wearing caps, participants wearing helmets overshoot distance estimations and were able to distinguish not only between targets situated at two depth levels as participants wearing caps could, but also between safe targets situated at wide and narrow visual angles. Our findings help define the interaction between safety devices and target type, thereby contributing to the debate between advocates of prevention models and those who maintain that these are offset by compensatory strategies.     

Size in the visual processing of faces and words

We studied the influence of variations of stimulus size upon recognition of words and faces. Size played an important role in the recognition of faces but was irrelevant to the recognition of words, over a range of sizes. More detailed analysis revealed that although irrelevant to recognition, size of words was nevertheless encoded, with some consequences similar to those for recognition of faces. The results were interpreted in terms of stimulus-specific analyses, and this view was contrasted with other notions of mental representation.