Auditory pattern recognition by untrained listeners

Earlier work with unpracticed Ss has indicated that identification (naming) of the temporal order of components within repeated sequences consisting of three or four unrelated sounds cannot be accomplished when the item durations are 200 msec or less. In the present experiment, separate groups of 30 unpracticed Ss were required to teil whether alternated sequences, each consisting of reiterated presentations of the same three or four successive items, were in identical or permuted order. Naming of the order within the sequences was not required. Accuracy of same/different judgments was significantly better than chance when all items lasted 200 msec. Changing the duration of each item in one of the two sequences above or below 200 msec made the task more difficult. These results, together with other evidence, suggest that: (1) identification of order and recognition of auditory temporal patterns may represent fundamentally different processes, and (2) recognition may involve matching of “temporal templates.”     

The joint role of trained,untrained, and observed actions at the origins of goal recognition

Recent findings across a variety of domains reveal the benefits of self-produced experience on object exploration, object knowledge, attention, and action perception. The influence of active experience may be particularly important in infancy, when motor development is undergoing great changes. Despite the importance of self-produced experience, we know that infants and young children are eventually able to gain knowledge through purely observational experience. In the current work, three-month-old infants were given experience with object-directed actions in one of three forms and their recognition of the goal of grasping actions was then assessed in a habituation paradigm. All infants were given the chance to manually interact with the toys without assistance (a difficult task for most three-month-olds). Two of the three groups were then given additional experience with object-directed actions, either through active training (in which Velcro mittens helped infants act more efficiently) or observational training. Findings support the conclusion that self-produced experience is uniquely informative for action perception and suggest that individual differences in spontaneous motor activity may interact with observational experience to inform action perception early in life.     

The role of edges in object recognition by pigeons

In three experiments, we explored how pigeons use edges, corresponding to orientation and depth discontinuities, in visual recognition tasks. In experiment 1, we compared the pigeon's ability to recognize line drawings of four different geons when trained with shaded images. The birds were trained with either a single view or five different views of each object. Because the five training views had markedly different appearances and locations of shaded surfaces, reflectance edges, etc, the pigeons might have been expected to rely more on the orientation and depth discontinuities that were preserved over rotation and in the line drawings. In neither condition, however, was there any transfer from the rendered images to the outline drawings. In experiment 2, some pigeons were trained with line drawings and shaded images of the same objects associated with the same response (consistent condition), whereas other pigeons were trained with a line drawing and a shaded image of two different objects associated with the same response (inconsistent condition). If the pigeons perceived any correspondence between the stimulus types, then birds in the consistent condition should have learned the discrimination more quickly than birds in the inconsistent condition. But, there was no difference in performance between birds in the consistent and inconsistent conditions. In experiment 3, we explored pigeons' processing of edges by comparing their discrimination of shaded images or line drawings of four objects. Once trained, the pigeons were tested with planar rotations of those objects. The pigeons exhibited different patterns of generalization depending on whether they were trained with line drawings or shaded images. The results of these three experiments suggest that pigeons may place greater importance on surface features indicating materials, such as food or water. Such substances do not have definite boundaries cued by edges which are thought to be central to human recognition.     

The role of letter recognition in word recognition

In a paradigm that avoids methodological problems of earlier studies, evidence was gathered addressed to the question of whether we read letter by letter. If word recognition involves letter recognition, then the difficulty of recognizing a word should vary with the difficulty of recognizing its letters. This was tested by assessing letter difficulty in two letter discrimination tasks and in a letter naming task, and then comparing 15 adult subjects' visual recognition latency to 72 easy-letter words and to 72 difficult-letter words. Word frequency and word length were also manipulated. Results indicated no effect for letter difficulty, although recognition latency reliably decreased with word frequency and monotonically increased with word length (21 msec/letter), suggesting that we do not read letter by letter, but that whatever plays a role in word recognition is smaller than the word and correlated with word length in letters.     

The role of familiarity in recognition

The role of familiarity in recognition was investigated by having subjects study a list of stimuli, some of which had been presented earlier in the experiment. The number of positive responses, both to targets and distractors, increased as a result of this familiarization process. This familiarization process had a greater effect on false alarms than on hits, so that recognition accuracy was lower for familiar stimuli than for relatively novel stimuli. This pattern of results differs from that found in most experiments studying the effects of linguistic word frequency on recognition.     

The role of generation in recognition

In contrast to the widely accepted opinion, a negatively accelerated RT function was obtained with varied mapping of stimuli to responses in Sternberg's (1966) recognition task when the task was designed to reduce proactive inhibition. These results are similar to the results obtained in the distractor task. Those aspects of the distractor task that proactively inhibit recall of the trigram are also necessary to produce a linear RT function in the recognition task. Hence, the varied-set procedure only results in a linear RT function when the memory sets on successive trials contain similar items, but not when successive trials contain different kinds of items, e.g., digits versus letters. Also, once subjects have been trained on the fixed-set procedure to produce a negatively accelerated RT function, the training transfers completely and immediately to entirely new sets of targets and distractors. The results of both tasks, as well as other retrieval tasks, can be explained by a model containing a single comparison process and an optional serial generation process which is invoked to increase the discriminability of the memory set from distractors.     

Social learning and acquired recognition of a predator by a marine fish

Predation is known to influence the distribution of behavioural traits among prey individuals, populations and communities over both evolutionary and ecological time scales. Prey have evolved mechanisms of rapidly learning the identity of predators. Chemical cues are often used by prey to assess predation risk especially in aquatic systems where visual cues are unreliable. Social learning is a method of threat assessment common among a variety of freshwater fish taxa, which incorporates chemosensory information. Learning predator identities through social learning is beneficial to na?ve individuals as it eliminates the need for direct interaction with a potential threat. Although social learning is widespread throughout the animal kingdom, no research on the use of this mechanism exists for marine species. In this study, we examined the role of social learning in predator recognition for a tropical damselfish, Acanthochromis polyacanthus. This species was found to not only possess and respond to conspecific chemical alarm cues, but na?ve individuals were able to learn a predators' identity from experienced individuals, the process of social learning. Fish that learned to associate risk with the olfactory cue of a predator responded with the same intensity as conspecifics that were exposed to a chemical alarm cue from a conspecific skin extract.     

The role of Afrocentric features in person perception: judging by features and categories

Four studies were conducted to test the hypothesis that group-related physical features may directly activate related stereotypes, leading to more stereotypic inferences over and above those resulting from categorization. As predicted, targets with more Afrocentric features were judged as more likely to have traits stereotypic of African Americans. This effect was found with judgments of African Americans and of European Americans. Furthermore, the effect was not eliminated when a more sensitive measure of categorization processes (category accessibility) was used or when the judgement context made category distinctions salient. Of additional interest was the finding that category accessibility independently affected judgment, such that targets who could be more quickly categorized as group members were judged more stereotypically.     

The role of proprioception in action recognition

This study aimed at evaluating the role of proprioception in the process of matching the final position of one's limbs with an intentional movement. Two experiments were realised with the same paradigm of conscious recognition of one's own limb position from a distorted position. In the first experiment, 22 healthy subjects performed the task in an active and in a passive condition. In the latter condition, proprioception was the only available information since the central signals related to the motor command were likely to be absent. The second experiment was realised with a deafferented patient who suffers from a complete haptic deafferentation, including loss of proprioception. The results first argue in favour of a dominant role of proprioception in action recognition, but they also stress the possible role of central signals. The process of matching the final position of one's limbs with an intended movement and thus of action recognition would be achieved through a comparison process between the predicted sensory consequences of the action, which are stored in its internal model, and the actual sensory consequences of that action.     

The role of context in object recognition

In the real world, objects never occur in isolation; they co-vary with other objects and particular environments, providing a rich source of contextual associations to be exploited by the visual system. A natural way of representing the context of an object is in terms of its relationship to other objects. Alternately, recent work has shown that a statistical summary of the scene provides a complementary and effective source of information for contextual inference, which enables humans to quickly guide their attention and eyes to regions of interest in natural scenes. A better understanding of how humans build such scene representations, and of the mechanisms of contextual analysis, will lead to a new generation of computer vision systems.     

The role of eyebrows in face recognition

A fundamental challenge in face recognition lies in determining which facial characteristics are important in the identification of faces. Several studies have indicated the significance of certain facial features in this regard, particularly internal ones such as the eyes and mouth. Surprisingly, however, one rather prominent facial feature has received little attention in this domain: the eyebrows. Past work has examined the role of eyebrows in emotional expression and nonverbal communication, as well as in facial aesthetics and sexual dimorphism. However, it has not been made clear whether the eyebrows play an important role in the identification of faces. Here, we report experimental results which suggest that for face recognition the eyebrows may be at least as influential as the eyes. Specifically, we find that the absence of eyebrows in familiar faces leads to a very large and significant disruption in recognition performance. In fact, a significantly greater decrement in face recognition is observed in the absence of eyebrows than in the absence of eyes. These results may have important implications for our understanding of the mechanisms of face recognition in humans as well as for the development of artificial face-recognition systems.     

The role of syntactic context in word recognition

This study examines the role of syntactic information in word recognition. Subjects made a word-nonword decision regarding a target string that was preceded by a syntactically appropriate word, a semantically related word, or an unrelated word. In Experiment 1, with syntactic and semantic trials assigned to separate blocks, syntactically and semantically appropriate context significantly reduced lexical decision for subsequent target words, compared with unrelated contexts. In Experiment 2, the syntactically and semantically primed trials were either blocked separately or mixed within the same block. Significant syntactic and semantic effects were both observed in the blocked condition, but only the semantic effect was obtained in the mixed condition     

The role of stimulus familiarity in context-dependent recognition

Memory & Cognition - Investigations of context-dependent recognition, a phenomenon in which recognition is better for items studied and tested with the same rather than different context, have...     

The role of audiovisual asynchrony in person recognition

Audiovisual integration (AVI) has been demonstrated to play a major role in speech comprehension. Previous research suggests that AVI in speech comprehension tolerates a temporal window of audiovisual asynchrony. However, few studies have employed audiovisual presentation to investigate AVI in person recognition. Here, participants completed an audiovisual voice familiarity task in which the synchrony of the auditory and visual stimuli was manipulated, and in which visual speaker identity could be corresponding or noncorresponding to the voice. Recognition of personally familiar voices systematically improved when corresponding visual speakers were presented near synchrony or with slight auditory lag. Moreover, when faces of different familiarity were presented with a voice, recognition accuracy suffered at near synchrony to slight auditory lag only. These results provide the first evidence for a temporal window for AVI in person recognition between approximately 100 ms auditory lead and 300 ms auditory lag.     

A polarity effect in misoriented object recognition: The role of polar features in the computation of orientation-invariant shape representations

This study investigated the contribution of polar features and internal shape axes to misoriented object recognition. A recognition memory paradigm was used to examine the effects of stimulus orientation on the recognition of previously memorized 2-D novel objects. In contrast to some recent reports, Experiment 1 showed that orientation-invariant performance can be found from the outset of testing with objects containing a salient axis of symmetry. In Experiments 2 and 3 it was found that the removal of a single salient polar feature, while preserving the axis of elongation, was sufficient to increase stimulus orientation time costs. This polarity effect suggests that polar features, and shape axes, play a role in the computation of orientation-invariant shape representations. It is proposed that shape axes facilitate the localization of polar features, which, in turn, are used to resolve the polarity of shape representations during recognition.     

Tits use amodal completion in predator recognition: a field experiment

Amodal completion enables an animal to perceive partly concealed objects as an entirety, and to interact with them appropriately. Several studies, based upon either operant conditioning or filial imprinting techniques, have shown that various animals (both mammals and birds) can perform amodal completion. Before this study, the use of amodal completion by untrained animals in the recognition of objects had not been considered. Using two feeders, we observed in a field experiment the reaction of tits to the torso of a sparrowhawk (partly occluded or an ‘amputated’ dummy) in two different treatments (sparrowhawk torso vs. complete dummy pigeon; and torso vs. complete dummy sparrowhawk). It is clear that the birds considered the two torso variants as predators and kept away from both of them when the second feeder offered a ‘pigeon’ instead. On the other hand, when a ‘complete sparrowhawk’ was present on the second feeder, the number of visits to the occluded torso remained low; while the number of visits to the amputated one increased threefold. Birds risked perching near what was clearly an amputated torso; while the fear of a “hiding” (occluded) torso remained unchanged, when the second feeder did not provide a safe alternative. Such discrimination between torsos requires the ability for amodal completion. Our results demonstrate that in their recognition process, the birds not only use simple sign stimuli, but also complex cognitive functions.     

The role of articulatory suppression in immediate false recognition

False memory for critical lures has been widely documented in long-term memory using the Deese/Roediger-McDermott paradigm. Recent evidence suggests that false memory effects can also be found in short-term memory (STM), supporting models that assume a strong relationship between short-term and long-term memory processes. However, no study has examined the role of articulatory suppression on immediate false memory, even though phono-articulatory factors are critically involved in STM performance and are an intrinsic part of all STM accounts. The current study proposes a novel paradigm to assess false memory effects in a STM task under both silent and articulatory suppression conditions. Using immediate serial recognition, in which participants had to judge whether two successive mixed lists of six associated and non-associated words were matched, we examined true recognition of matching lists and false recognition of mismatching lists comprising a critical lure or unrelated distractor in two experiments. Results from both experiments indicated reduced true recognition of matching lists and greater false serial recognition of mismatching lists comprising a critical lure under articulatory suppression relative to silence. These findings provide further support for some current models of verbal short-term memory, which posit a strong relationship between short-term and long-term memory processes.     

The role of rigid motion in newborns' face recognition

The study investigated whether dynamic information promotes newborns' ability to recognize a face. After being habituated to a face undergoing an ordered sequential head rigid motion (Exp. 1), 1- to 3-day-old newborns fully recognized the familiar face shown in the profile pose, as documented by a preference for the profile pose of a novel face. When familiarized to an ordered sequence of different viewpoint static images of a face (Exp. 2), newborns failed to recognize the profile pose of the familiar face, their visual exploration of the familiar and novel faces being at chance. Habituation to a random head rigid motion (Exp. 3) allowed only a partial recognition of face identity, as newborns preferred the profile pose of the familiar, rather than the novel, face. Rigid head motion is an important source of information for newborns' face recognition, probably aiding the derivation of a three-dimensional face structure.     

The role of spurious feature familiarity in recognition memory

In two experiments, we investigated the role of perceptual information in spurious recognition judgments. Participants viewed lists of words in various unusual fonts. The frequency with which each font was presented was manipulated at study: Each font was presented with 1 or 12 different words in Experiment 1 and with 1 or 20 words in Experiment 2. Although the participants were instructed in a word recognition test to judge only on the basis of the word, regardless of font, there were significantly more false alarms for new words seen in a previously presented font than for new words presented in a novel (not seen at study) font in Experiment 1. In Experiment 2, the participants were significantly more likely to make a false alarm to a new word seen in a font that had been used to present 20 words during study than to a font that had been used to present only 1 word during study. The data show a mirror effect, in which words tested in low-frequency fonts produced more hits and fewer false alarms than did words tested in high-frequency fonts. These results show that irrelevant perceptual information plays a role in recognition judgments by providing spurious sources of familiarity and, thus, provide evidence that perceptual information is represented and processed in the same way as semantic information.