Perceptual interference and hemispheric specialization

Two experiments evaluated the effect of stimuli presented at fixation on the recognition of faces or random shapes presented to the left or right visual half-field (VF). Increasing the processing demands of the center stimulus produced a large, linear decrease in recognition from both VFs for both faces and shapes. Recognition of random shapes was decreased more in the right visual field by center digits and in the left VF by center faces and shapes. In addition, interference was found between the VF faces and the center digits to the left of fixation. It was concluded that differences in the processing capacity of the two hemispheres are a function of the verbal-nonverbal nature of the stimuli at a later stage in processing but that the two hemispheres may also differ along other perceptual dimensions at an earlier stage of visual recognition.     

Odor recognition: familiarity, identifiability, and encoding consistency

The investigation examined the association between the perceived identity of odorous stimuli and the ability to recognize the previous occurrence of them. The stimuli comprised 20 relatively familiar odorous objects such as chocolate, leather, popcorn, and soy sauce. Participants rated the familiarity of the odors and sought to identify them. At various intervals up to 7 days after initial inspection, the participants sought to recognize the odors among sets of distractor odors that included such items as soap, cloves, pipe tobacco, and so on. The recognition response entailed a confidence rating as to whether or not an item had appeared in the original set. At the time of testing, the participants also sought to identify the stimuli again. The results upheld previous findings of excellent initial recognition memory for environmentally relevant odors and slow forgetting. The results also uncovered, for the first time, a strong association between recognition memory and identifiability, rated familiarity, and the ability to use an odor label consistently at inspection and subsequent testing. Encodability seems to enhance rather than to permit recognizability. Even items identified incorrectly or inconsistently were recognized at levels above chance.     

Recognition memory for objects in very young children: The effect of shape and label similarity on preference for novel stimuli

In two studies, 88 children 12 to 38 months of age were briefly shown 24 common objects on familiarization trials. On subsequent test trials, these objects reappeared paired with novel objects. On one-third of the test trials pairs were similar in shape, on another third of the test trials pairs shared a common label, and on the remaining test trials pairs were unrelated. Looking times for each of the two objects on test trials were measured. All but the youngest age group showed significantly longer looking times for novel than for familiar objects for all three kinds of test pairs. However, for 19- to 31-month-olds preference for novel stimuli in the common Label Condition, although significant, was less than preference for novel stimuli when shape was similar or when unrelated stimuli were paired. Recognition in the oldest group was unaffected by condition. The results suggest a developmental period during which label or conceptual similarity has a special significance for recognition, and are discussed within theoretical frameworks concerning the very young child's developing semantic and categorization skills.     

Serial position effects in recognition memory for odors: A reexamination

Seven experiments examined recognition memory for sequentially presented odors. Following Reed (2000), participants were presented with a sequence of odors and then required to identify an odor from the sequence in a test probe comprising 2 odors. The pattern of results obtained by Reed (2000, although statistically marginal) demonstrated enhanced recognition for odors presented at the start (primacy) and end (recency) of the sequence: a result that we failed to replicate in any of the experiments reported here. Experiments 1 and 3 were designed to replicate Reed (2000), employing five-item and seven-item sequences, respectively, and each demonstrated significant recency, with evidence of primacy in Experiment 3 only. Experiment 2 replicated Experiment 1, with reduced interstimulus intervals, and produced a null effect of serial position. The ease with which the odors could be verbally labeled was manipulated in Experiments 4 and 5. Nameable odors produced a null effect of serial position (Experiment 4), and hard-to-name odors produced a pronounced recency effect (Experiment 5); nevertheless, overall rates of recognition were remarkably similar for the two experiments at around 70%. Articulatory suppression reduced recognition accuracy (Experiment 6), but recency was again present in the absence of primacy. Odor recognition performance was immune to the effects of an interleaved odor (Experiment 7), and, again, both primacy and recency effects were absent. There was no evidence of olfactory fatigue: Recognition accuracy improved across trials (Experiment 1). It is argued that the results of the experiments reported here are generally consistent with that body of work employing hard-to-name visual stimuli, where recency is obtained in the absence of primacy when the retention interval is short.     

Recall of odors: naming and autobiographical memories illustrate odor aftereffects

In the study phase, subjects had to encode either odors or the names there of by generating autobiographical memories, by judging the quality of the food source of the odors, or by labeling responses to odors. At the testing stage, explicit and implicit olfactory memory performance was assessed. With recognition testing, the provision of odors at study improved performance. Furthermore, recognition depended on elaborative encoding conditions with olfactory stimuli only. Implicit memory was measured by the correctness and speed of labeling responses at the testing stage. Old odors were named more correctly and faster than new ones, but only if subjects had encoded odors in the study phase. These results demonstrate that implicit memory in naming odors depends on olfactory stimulus processing and is not a purely verbal priming effect. As a further measure of implicit memory, the speed of autobiographical memory productions was assessed. We registered shorter reaction times for old versus new odors. But again, this effect of implicit memory was restricted to conditions of odor pre-experiences in the study phase. We conclude that olfactory memory is based on different types of memory traces. Implicit memory measures may prove to be useful in isolating sensory and other attributes of olfaction that seem to be interacting in making explicit memory judgments.     

The influence of chemical complexity on the perception of multicomponent odor mixtures

The present study investigates the hypothesis that complexobject odors (odors that emanate from flowers, foods, sewage, etc.) that consist of dozens of odorants are processed and encoded as discrete entities, as if each was a single chemical odor. To test this hypothesis, the capacity of trained subjects to discriminate and identify the components of stimuli consisting of one to eight object odors was determined. The results indicated that subjects could only identify up to four object odors in a mixture, which is similar to earlier findings with mixtures that contained only single chemical odors. The limited capacity was also reflected in the number of odors selected, regardless of whether the choices were correct or incorrect, in confidence ratings, and in decision times. The identification of a limited number of object odors in every mixture that was presented suggests that both associative (synthetic) and dissociative (analytic) processes are involved in the perceptual analysis of odor mixtures.     

Encoding processes in recognition and recall

The present experiments demonstrate that picture-word stimuli are differentially encoded in anticipation of a recognition test than in anticipation of a free-recall test. Subjects perform better on the retention test of which they have been informed, and different information from the stimuli is used to pass each test. These findings cannot be attributed to stimulus selection nor to pure pictorial encoding in anticipation of recognition and pure verbal encoding in anticipation of recall. Recognition is enhanced by encoding which integrates the details within each item while recall is enhanced by encoding which interrelates the items of a list.     

Memory for pictograms, pictures, and words separately and all mixed up

Pictograms were created in which the outline of a work denoting an object was shaped to be the same as the object itself. A number of objects were presented, some drawn as pictograms, some as outline shapes, and some as normally printed words. The experiment was designed to test if recognition memory was superior for the pictograms as compared to outline pictures or words, and if this would be true whether the subjects were asked to attend to the form or only the content of the stimuli. One group of subjects was trained to respond OLD only if the test item was the same object in the same form, and NEW only to objects never before shown in any form. Recognition accuracy (a signal detection analysis) was greatest for the pictograms, and poorest for the words in both groups. Though the subjects could disregard form, they were most accurate when probed with the same form as presented. But in all comparisons subjects were most accurate when forced to recall both the form and the content. These and other results were taken to be mildly supportive of a dual coding hypothesis, and of the utility of these new stimuli.     

Task difficulty and visual similarity increase a distractor's effects on random shapes

Recognition of random shapes followed by a visual distractor is altered by the type of distractor and whether the distractor needs to be attended. Three experiments tested which characteristics modify a visual distractor's effect on random target shapes presented for 75 to 150 msec. Exp. 1 showed that increasing the number of digits to be remembered (1, 3, or 8) increased the effectiveness of digits as distractors. Exeir effect as visual distractors for random target shapes. Random shapes were highly effective as distractors, while pictures of faces or comples colored pictures had a relatively small effect. In Exp. 3 decreasing the presentation time for novel visual distractors decreased recognition of the distractors but not of random target shapes. However, adding a three-digit distractor after the novel visual distractor did decrease recognition of target shapes. Exps. 2 and 3 showed that the order of the recognition tests of the target and distracting stimuli altered target recognition if and only if subjects did know which was to be reported first. These experiments indicate that the effect of a visual distractor depends on both the extent to which it is allotted attention and its visual similarity to the target stimulus.     

Attention misplaced: the role of diagnostic features in the face-inversion effect

Inversion disproportionately impairs recognition of face stimuli compared to nonface stimuli arguably due to the holistic manner in which faces are processed. A qualification is put forward in which the first point fixated on is different for upright and inverted faces and this carries some of the face-inversion effect. Three experiments explored this possibility by using fixation crosses to guide attention to the eye or mouth region of the to-be-presented faces in different orientations. Recognition was better when the fixation cross appeared at the eye region than at the mouth region. The face-inversion effect was smaller when the eyes were cued than when the mouth was cued or when there was no cueing. The results suggest that the first facial feature attended to is important for accurate face recognition and this may carry some of the effects of inversion.     

Recognition memory for faces: When familiarity supports associative recognition judgments

Recognition memory for single items can be dissociated from recognition memory for the associations between items. For example, recognition tests for single words produce curvilinear receiver operating characteristics (ROCs), but associative recognition tests for word pairs produce linear ROCs. These dissociations are consistent with dual-process theories of recognition and suggest that associative recognition relies on recollection but that item recognition relies on a combination of recollection and assessments of familiarity. In the present study, we examined associative recognition ROCs for facial stimuli by manipulating the central and external features, in order to determine whether linear ROCs would be observed for stimuli other than arbitrary word pairs. When the faces were presented upright, familiarity estimates were significantly above zero, and the associative ROCs were curvilinear, suggesting that familiarity contributed to associative judgments. However, presenting the faces upside down effectively eliminated the contribution of familiarity to associative recognition, and the ROCs were linear. The results suggest that familiarity can support associative recognition judgments, if the associated components are encoded as a coherent gestalt, as in upright faces.     

Relations Among Early Object Recognition Skills: Objects and Letters

Human visual object recognition is multifaceted and comprised of several domains of expertise. Developmental relations between young children's letter recognition and their 3-dimensional object recognition abilities are implicated on several grounds but have received little research attention. Here, we ask how preschoolers' success in recognizing letters relates to their ability to recognize 3-dimensional objects from sparse shape information alone. Seventy-three 2 1/2 to 5-year-old children completed a “Letter Recognition” task, measuring the ability to identify a named letter among 3 letters, and a “Shape Caricature Recognition” task, measuring recognition of familiar objects from sparse, abstract information about their part shapes and the spatial relations among those parts. Children also completed a control “Shape Bias” task, in which success depends on matching exact shapes but not on building an internal representation of the configuration of features characteristic of an object category or letter. Children's success in letter recognition was positively related to their shape caricature recognition scores, but not to their shape bias scores. The results suggest that letter recognition builds upon developing skills in attending to and representing the relational structure of object shape, and that these skills are common to both 2-dimensional and 3-dimensional object perception.     

Caricature and face recognition

Although caricatures are often gross distortions of faces, they frequently appear to be super-portraits capable of eliciting recognition better than veridical depictions. This may occur because faces are encoded as distinctive feature deviations from a prototype. The exaggeration of these deviations in a caricature may enhance recognition because it emphasizes the features of the face that are encoded. In two experiments, we tested the superportrait hypothesis and the encoding-by-caricature hypothesis. In the first experiment, caricatures were recognized better than faces, and true caricatures of previously seen faces were recognized better than the faces from which the caricatures had been developed. In the second experiment, faces and their caricatures were tachistoscopically presented in a sequential same/different reaction time task. Subjects were slower to distinguish the stimuli when the face preceded its caricature, indicating that caricatures are more similar to the encoded representation of a face than are stimuli in which the distinctive features are deemphasized.     

VIEWPOINT DEPENDENCE IN SCENE RECOGNITION

Abstract— Two experiments investigated the viewpoint dependence of spatial memories. In Experiment 1, participants learned the locations of objects on a desktop from a single perspective and then took part in a recognition test, test scenes included familiar and novel views of the layout. Recognition latency was a linear function of the angular distance between a test view and the study view. In Experiment 2, participants studied a layout from a single view and then learned to recognize the layout from three additional training views. A final recognition test showed that the study view and the training views were represented in memory, and that latency was a linear function of the angular distance to the nearest study or training view. These results indicate that interobject spatial relations are encoded in a viewpoint-dependent manner, and that recognition of novel views requires normalization to the most similar representation in memory. These findings parallel recent results in visual object recognition     

Developmental change and cross‐domain links in vocal and musical emotion recognition performance in childhood

Although the configurations of psychoacoustic cues signalling emotions in human vocalizations and instrumental music are very similar, cross‐domain links in recognition performance have yet to be studied developmentally. Two hundred and twenty 5‐ to 10‐year‐old children were asked to identify musical excerpts and vocalizations as happy, sad, or fearful. The results revealed age‐related increases in overall recognition performance with significant correlations across vocal and musical conditions at all developmental stages. Recognition scores were greater for musical than vocal stimuli and were superior in females compared with males. These results confirm that recognition of emotions in vocal and musical stimuli is linked by 5 years and that sensitivity to emotions in auditory stimuli is influenced by age and gender.     

Recognizing faces defined by texture gradients

Texture gradients can reveal surface orientation in a manner similar to shape from shading, and therefore provide an important cue for object recognition. In this study, we tested whether a complex 3-D object, such as a face, can be identified from texture gradients alone. The stimuli were laser-scanned faces for which the texture element was a fractal-noise pattern mapped onto the 3-D surface. An eight-alternative forced choice task was used in which participants matched a face defined by texture gradients to one of eight faces defined by shape from shading (Experiment 1) or by texture gradients (Experiment 2). On average, participants scored 24% and 18%, respectively, above chance in these experiments. Although this performance was much poorer than the performance based entirely on shape-from-shading stimuli (Experiment 3), the results suggest that texture gradient information may be used to recover surface geometry of complex objects.     

Attentional biases and memory for emotional stimuli in men and male rhesus monkeys

We examined attentional biases for social and non-social emotional stimuli in young adult men and compared the results to those of male rhesus monkeys (Macaca mulatta) previously tested in a similar dot-probe task (King et al. in Psychoneuroendocrinology 37(3):396–409, 2012). Recognition memory for these stimuli was also analyzed in each species, using a recognition memory task in humans and a delayed non-matching-to-sample task in monkeys. We found that both humans and monkeys displayed a similar pattern of attentional biases toward threatening facial expressions of conspecifics. The bias was significant in monkeys and of marginal significance in humans. In addition, humans, but not monkeys, exhibited an attentional bias away from negative non-social images. Attentional biases for social and non-social threat differed significantly, with both species showing a pattern of vigilance toward negative social images and avoidance of negative non-social images. Positive stimuli did not elicit significant attentional biases for either species. In humans, emotional content facilitated the recognition of non-social images, but no effect of emotion was found for the recognition of social images. Recognition accuracy was not affected by emotion in monkeys, but response times were faster for negative relative to positive images. Altogether, these results suggest shared mechanisms of social attention in humans and monkeys, with both species showing a pattern of selective attention toward threatening faces of conspecifics. These data are consistent with the view that selective vigilance to social threat is the result of evolutionary constraints. Yet, selective attention to threat was weaker in humans than in monkeys, suggesting that regulatory mechanisms enable non-anxious humans to reduce sensitivity to social threat in this paradigm, likely through enhanced prefrontal control and reduced amygdala activation. In addition, the findings emphasize important differences in attentional biases to social versus non-social threat in both species. Differences in the impact of emotional stimuli on recognition memory between monkeys and humans will require further study, as methodological differences in the recognition tasks may have affected the results.     

Sensory and semantic factors in recognition memory for odors and graphic stimuli: elderly versus young persons

In four experiments, young (18-26 years, M = 21) and elderly (over 65 years, M = 72) people were compared for recognition memory of (a) graphic stimuli (faces of presidents and vice presidents, engineering symbols, and free forms) and (b) everyday odors. On graphic stimuli, the elderly consistently matched the young, but on odors the performance of the elderly was worse. Their poorer olfactory performance was observed after only 26 s, but became truly marked after 1 hr or more. Somewhere between 1 hr and 2 weeks, their odor performance fell to chance, but their graphic performance remained well above chance. Although the young did forget both graphic and odor materials progressively, their performance always stayed above chance over a 6-month period. Experiments 1 and 2 revealed that the elderly are less sensitive to odors than the young (with thresholds about 10-fold higher), which may explain, in part, their poorer olfactory memory performance. Knowledge that the subjects brought to the tasks by way of familiarity with and ability to name odors and faces played a positive role in recognition memory. Because of this positive role, together with the negative role played by verbal distraction, we conclude that odor recognition memory depends, perhaps heavily, on semantic processing. Impaired semantic processing may result even when odors are simply rendered desaturated, or pastel because of the weakening of olfactory sensitivity with aging.     

Species-specific danger signals, endogenous opioid analgesia, and defensive behavior

The effects of handling stimuli and stress odors on species-specific defensive behavior and pain sensitivity were examined in rats. Animals not adapted to handling had longer jump latencies on the hot plate test of pain sensitivity than those with extensive handling experience. In a postshock freezing test, naltrexone enhanced defensive freezing relative to saline controls in nonadapted animals. However, naltrexone produced no such effect in rats that were adapted to handling. These two studies indicate that the handling procedure triggered an endogenous opioid analgesic response in rats not adapted to handling. Experiment 3 showed that a similar naltrexone-reversible opioid analgesia can be triggered by stress odors. Naltrexone, when compared to saline, enhanced postshock freezing in the presence of conspecific stress odors, but not in their absence. In Experiment 4, stress odors and nonadapted handling were able to activate defensive freezing directly, when tested in compound but not in isolation. The studies are consistent with the view that stress odors and handling stimuli are danger signals that activate endogenous opioid analgesia as well as defensive behavior, suggesting that analgesia is a component of the rat's defensive behavior system.     

Role of verbal encoding in shortand long-term odor recognition

The role of verbal encoding in odor recognition memory was investigated using odors of low familiarity to subjects before the experiment began. The experimental procedure included two phases—odor learning (first phase) and odor memory testing (second phase)—separated by a delay of 7 days. Five experimental conditions were established: three conditions of odor learning with names (labeling conditions), one condition of odor learning without names (sensory familiarization), and one condition of no learning prior to testing (control conditions). The labeling conditions differed from each other regarding label characteristics. The names were those of odor sources (veridical names), those personally generated by subjects (generated names), or those derived from the chemical names of the odorants (chemical names). Subjects were required to learn 20 fixed associations between odors (targets or distractors) and 20 names during two daily sessions. The learning sessions included two identification tests and ended by a verbal memory test in which subjects recalled odor names. The odor memory test was split into two parts separated by a retention interval of either 20 min (short-term memory) or 24 h (long-term memory). Data showed that olfactory recognition memory was enhanced in subjects who associated veridical or generated names to odors during the learning session. Chemical names were not appropriate to facilitate odor recognition. Similarly, the level of odor identification was higher for veridical and generated names than for chemical names, though the level of verbal memory for chemical names was substantial. Recognition response latencies were systematically longer for a target odor implying a positive response than for a distractor odor implying a negative response. Together, these data suggest that odor recognition and identification are sensitive to the semantic content of labels associated with odors. Odor memory was adversively influenced by time, but this influence was less pronounced when the names were endowed with a rich semantic content.