The mind's nose: Effects of odor and visual imagery on odor detection

Abstract— We examined odor imagery by looking for its effects on detection of weak odors. Seventy-two healthy subjects performed a forced-choice odor detection task in one of three conditions: after being told to imagine an odor (odor imagery), after being told to imagine an object (visual imagery), or without having received imagery instructions (no-imagery control). For the two imagery conditions, the presented and imagined stimuli were either the same (matched) or different (mismatched). There was a significant difference between detection in the matched and mismatched conditions for odor imagery, but not for visual imagery. We conclude that our paradigm does measure odor imagery and that the effect of imagery on detection is both content- and modality-specific. Further, the difference between conditions was due to lower detection with mismatched odor imagery than without imagery, indicating that interference underlies the effect.     

Selective interference during the retrieval of visual images

Twenty-six subjects memorized lists of (low I and high I) noun pairs under imagery or verbal mediation instructions. At recall the subjects were presented a digit (“1” or “2”) either auditorily or visually as an interfering stimulus.

Visual interference was found to selectively affect the retrieval of high I response terms. Also, the retrieval of nouns studied by imagery mediation was found to be selectively disrupted by visual interference.

These results suggest that the qualities of a visual image are retained all the way from image acquisition to retrieval, and that the visual components of images generated at the acquisition stage are probably not lost by subsequent coding processes.     

An experimental study of visual imagination and memory

It is shown that an irrelevant visual perception interferes more with verbal learning by means of imagery than does an irrelevant auditory perception. The relative interfering effects of these perceptions were reversed in a verbal learning task involving highly abstract materials. Such results implicate the existence of a true visual component in imaginal mediation. A theoretical model is presented in which a visual system and a verbal-auditory system are distinguished. The visual system controls visual perception and visual imagination. The verbal-auditory system controls auditory perception, auditory imagination, internal verbal representation, and speech. Attention can be more easily divided between the two systems than within either one taken by itself. Furthermore, the visual and verbal-auditory systems are functionally linked by information recoding operations. The application of mnemonic imagery appears to involve a recoding of initially verbal information into visual form, and then the encoding of a primarily visual schema into memory. During recall, the schema is decoded as a visual image, and then recoded once again into the verbal-auditory system. Evidence for such transformations is provided not only by the interference data, but also by an analysis of recall-errors made by Ss using mnemonic imagery.     

The form of analog size information in memory

The information used to choose the larger of two objects from memory was investigated in two experiments that compared the effects of a number of variables on the performance of subjects who either were instructed to use imagery in the comparison task or were not so instructed. Subjects instructed to use imagery could perform the task more quickly if they prepared themselves with an image of one of the objects at its normal size, rather than with an image that was abnormally big or small, or no image at all. Such subjects were also subject to substantial selective interference when asked to simultaneously maintain irrelevant images of digits. In contrast, when subjects were not specifically instructed to use imagery to reach their decisions, an initial image at normal size did not produce significantly faster decisions than no image, or a large or small image congruent with the correct decision. The selective interference created by simultaneously imaging digits was reduced for subjects not told to base their size comparisons on imagery. The difficulty of the size discrimination did not interact significantly with any other variable. The results suggest that subjects, unless specifically instructed to use imagery, can compare the size of objects in memory using information more abstract than visual imagery.     

听觉诱发表象的眼动机制

视觉心理表象是一种基于过去经验的自上而下的加工过程,它是信息表征的一种形式.以往的研究主要采用视觉来诱发表象,但是这很难排除视觉后像的干扰,而且与表象“自上而下”的加工过程不一致.听觉诱发表象很好地解决了视觉后像的干扰问题,也更吻合表象“自上而下”的加工过程,因为被试产生的表象是基于自己过去的经验,从自身出发,主动加工的结果.采用实验法,考察通过听觉通道诱发表象眼动的情况,使用眼动仪记录被试的眼动轨迹.结果发现：（1）不管是运动还是静止的物体,都能诱发表象,在表象时存在眼动行为.（2）运动的物体诱发眼动的程度更大.（3）眼动影响表象的建构,在表象建构中起机能性作用.     

Item concreteness vs spatial organization as predictors of visual imagery

The relative contributions of item concreteness and interitem spatial organization to recall processes were studied by attempting to induce modality-specific interference between recall and response. Separate groups of 12 Ss learned lists of items that varied in physical or referential visual characteristics. They later signaled information about them either vocally or via a visually guided response. Some ways of presenting lists for learning that are traditionally regarded as increasing reliance on mediating imagery were effective in generating conflict between recall and the visually guided response. This effectiveness was limited to presentation conditions and list types that introduced spatial organization into the stimulus material. The concreteness of individual items was not useful in predicting visual conflict.     

Visuospatial tasks suppress craving for cigarettes

The Elaborated Intrusion (EI) theory of desire posits that visual imagery plays a key role in craving. We report a series of experiments testing this hypothesis in a drug addiction context. Experiment 1 showed that a mental visual imagery task with neutral content reduced cigarette craving in abstaining smokers, but that an equivalent auditory task did not. The effect of visual imagery was replicated in Experiment 2, which also showed comparable effects of non-imagery visual working memory interference. Experiment 3 showed that the benefit of visual over auditory interference was not dependent upon imagery being used to induce craving. Experiment 4 compared a visuomotor task, making shapes from modeling clay, with a verbal task (counting back from 100), and again showed a benefit of the visual over the non-visual task.We conclude that visual imagery supports craving for cigarettes. Competing imagery or visual working memory tasks may help tackle craving in smokers trying to quit.     

The effectiveness of imagery and sentence strategy instructions as a function of visual and auditory processing in young school-age children

The relationship between auditory and visual processing modality and strategy instructions was examined in first- and second-grade children. A Pictograph Sentence Memory Test was used to determine dominant processing modality as well as to assess instructional effects. The pictograph task was given first followed by auditory or visual interference. Children who were disrupted more by visual interference were classed as visual processors and those more disrupted by auditory interference were classed as auditory processors. Auditory and visual processors were then assigned to one of three conditions: interactive imagery strategy, sentence strategy, or a control group. Children in the imagery and sentence strategy groups were briefly taught to integrate the pictographs in order to remember them better. The sentence strategy was found to be effective for both auditory and visual processors, whereas the interactive imagery strategy was effective only for auditory processors.     

Visual mental image generation does not overlap with visual short-term memory: A dual-task interference study

Visual mental imagery and working memory are often assumed to play similar roles in high-order functions, but little is known of their functional relationship. In this study, we investigated whether similar cognitive processes are involved in the generation of visual mental images, in short-term retention of those mental images, and in short-term retention of visual information. Participants encoded and recalled visually or aurally presented sequences of letters under two interference conditions: spatial tapping or irrelevant visual input (IVI). In Experiment 1, spatial tapping selectively interfered with the retention of sequences of letters when participants generated visual mental images from aural presentation of the letter names and when the letters were presented visually. In Experiment 2, encoding of the sequences was disrupted by both interference tasks. However, in Experiment 3, IVI interfered with the generation of the mental images, but not with their retention, whereas spatial tapping was more disruptive during retention than during encoding. Results suggest that the temporary retention of visual mental images and of visual information may be supported by the same visual short-term memory store but that this store is not involved in image generation.     

Effects of same-modality interference on immediate serial recall of auditory and visual information.

Two studies investigated the effects of same-modality interference on the immediate serial recall of auditorily and visually presented stimuli. Typically, research in which this task is used has been conducted in quiet rooms, excluding auditory information that is extraneous to the auditorily presented stimuli. However, visual information such as background items clearly within the subject's view have not been excluded during visual presentation. Therefore, in both the present studies, the authors used procedures that eliminated extra-list visual interference and introduced extra-list auditory interference. When same-modality interference was eliminated, weak visual recency effects were found, but they were smaller than those that were generated by auditorily presented items. Further, mid-list and end-of-list recall of visually presented stimuli was unaffected by the amount of interfering visual information. On the other hand, the introduction of auditory interference increased mid-list recall of auditory stimuli. The results of Experiment 2 showed that the mid-list effect occurred with a moderate, but not with a minimal or maximal, level of auditory interference, indicating that moderate amounts of auditory interference had an alerting effect that is not present in typical visual interference.     

Visual imagery and the discrimination of differences between altered pictures simultaneously and successively presented.

Ten 'good' visual imagers and ten 'poor' imagers, representing the upper and lower halves of an unselected sample of adult volunteers, were given a task of detecting differences between altered pictures presented in pairs, either simultaneously or successively. Performance was measured by reaction time. 'Good' imagers reacted faster than 'poor' imagers, and the mode of presentation (simultaneous v. successive) did not affect their performances. 'Poor' imagers, on the other hand, reacted significantly slower when the pictures compared were presented successively. The results suggest that self-rated visual imagery can be used to predict the successful recall of visual information required in a discrimination task.     

Semantic interference from visual object recognition on visual imagery

A new technique for examining the interaction between visual object recognition and visual imagery is reported. The "image-picture interference" paradigm requires participants to generate and make a response to a mental image of a previously memorized object, while ignoring a simultaneously presented picture distractor. Responses in 2 imagery tasks (making left-right higher spatial judgments and making taller-wider judgments) were longer when the simultaneous picture distractor was categorically related to the target distractor relative to unrelated and neutral target-distractor combinations. In contrast, performance was not influenced in this way when the distractor was a related word, when a semantic categorization decision was made to the target, or when distractor and target were visually but not categorically related to one another. The authors discuss these findings in terms of the semantic representations shared by visual object recognition and visual imagery that mediate performance.     

Face imagery is based on featural representations

The effect of imagery on featural and configural face processing was investigated using blurred and scrambled faces. By means of blurring, featural information is reduced; by scrambling a face into its constituent parts configural information is lost. Twenty-four participants learned ten faces together with the sound of a name. In following matching-to-sample tasks participants had to decide whether an auditory presented name belonged to a visually presented scrambled or blurred face in two experimental conditions. In the imagery condition, the name was presented prior to the visual stimulus and participants were required to imagine the corresponding face as clearly and vividly as possible. In the perception condition name and test face were presented simultaneously, thus no facilitation via mental imagery was possible. Analyses of the hit values showed that in the imagery condition scrambled faces were recognized significantly better than blurred faces whereas there was no such effect for the perception condition. The results suggest that mental imagery activates featural representations more than configural representations.     

Dynamic visual noise reduces confidence in short-term memory for visual information

Previous research has shown effects of the visual interference technique, dynamic visual noise (DVN), on visual imagery, but not on visual short-term memory, unless retention of precise visual detail is required. This study tested the prediction that DVN does also affect retention of gross visual information, specifically by reducing confidence. Participants performed a matrix pattern memory task with three retention interval interference conditions (DVN, static visual noise and no interference control) that varied from trial to trial. At recall, participants indicated whether or not they were sure of their responses. As in previous research, DVN did not impair recall accuracy or latency on the task, but it did reduce recall confidence relative to static visual noise and no interference. We conclude that DVN does distort visual representations in short-term memory, but standard coarse-grained recall measures are insensitive to these distortions.     

Individual differences in visual imagery determine how event information is remembered

Individuals differ in how they mentally imagine past events. When reminiscing about a past experience, some individuals remember the event accompanied by rich visual images, while others will remember it with few of these images. In spite of the implications that these differences in the use of imagery have to the understanding of human memory, few studies have taken them into consideration. We examined how imagery interference affecting event memory retrieval was differently modulated by spatial and object imagery ability. We presented participants with a series of video-clips depicting complex events. Participants subsequently answered true/false questions related to event, spatial, or feature details contained in the videos, while simultaneously viewing stimuli that interfered with visual imagery processes (dynamic visual noise; DVN) or a control grey screen. The impact of DVN on memory accuracy was related to individual differences in spatial imagery ability. Individuals high in spatial imagery were less accurate at recalling details from the videos when simultaneously viewing the DVN stimuli compared to those low in spatial imagery ability. This finding held for questions related to the event and spatial details but not feature details. This study advocates for the inclusion of individual differences when studying memory processes.     

Coding strategies and cerebral laterality effects

In a short-term recognition memory task, Ss were given relational imagery and rehearsal coding strategies in different sessions, with probes presented to the left or right cerebral hemisphere. Consistent with a model of separate processing systems for verbally and visually coded information, Ss yielded significantly faster response latencies for probes to the left hemisphere than the right when employing the rehearsal strategy, and significantly faster latencies for probes to the right hemisphere than the left when using the imagery code. This suggests that cerebral laterality effects are functionally related to coding strategies, and argues for the inclusion of imagery, or generated visual information, as part of the visual processing system. As such, generated visual information may be viewed as a coding alternative to verbal mediation.     

Stroop interference in the left and right visual fields

The Stroop Color-Word test was employed to study the amount of interference in naming colors when stimuli were presented in either visual field. It was hypothesized that more Stroop interference would occur in the dominant hemisphere. The subjects were 24 right-handed college students, between 18 and 25 years old. There were three conditions in each visual field: Interference, Reading, and Naming. Each slide was presented for 150 msec preceded by a fixation dot. Subjects were asked to verbally report as fast and as accurately as they could either the color words or the color names, depending upon the conditions. Reaction times and error rates were analyzed. As expected, significantly higher error rates were obtained when color words were presented in the right visual field under the Stroop interference condition. Under this same condition, reaction time analysis yielded no significant differences between hemispheres.     

Cerebral Organization of Motor Imagery: Contralateral Control of Grip Selection in Mentally Represented Prehension

The principle of contralateral organization of the visual and motor systems was exploited to investigate contributions of the cerebral hemispheres to the mental representation of prehension in healthy, right-handed human subjects. Graphically rendered dowels were presented to either the left or right visual field in a variety of different orientations, and times to determine whether an underhand or overhand grip would be preferred for engaging these stimuli were measured. Although no actual reaching movements were performed, a significant advantage in grip-selection time was found when information was presented to the cerebral hemisphere contralateral to the designated response hand. Results are consistent with the position that motor imagery recruits neurocognitive mechanisms involved in movement planning. More precisely, these findings indicate that processes within each cerebral hemisphere participate in mentally representing object-oriented actions of the contralateral hand.     

The drawing effect: Evidence for reliable and robust memory benefits in free recall

In 7 free-recall experiments, the benefit of creating drawings of to-be-remembered information relative to writing was examined as a mnemonic strategy. In Experiments 1 and 2, participants were presented with a list of words and were asked to either draw or write out each. Drawn words were better recalled than written. Experiments 3–5 showed that the memory boost provided by drawing could not be explained by elaborative encoding (deep level of processing, LoP), visual imagery, or picture superiority, respectively. In Experiment 6, we explored potential limitations of the drawing effect, by reducing encoding time and increasing list length. Drawing, relative to writing, still benefited memory despite these constraints. In Experiment 7, the drawing effect was significant even when encoding trial types were compared in pure lists between participants, inconsistent with a distinctiveness account. Together these experiments indicate that drawing enhances memory relative to writing, across settings, instructions, and alternate encoding strategies, both within- and between-participants, and that a deep LoP, visual imagery, or picture superiority, alone or collectively, are not sufficient to explain the observed effect. We propose that drawing improves memory by encouraging a seamless integration of semantic, visual, and motor aspects of a memory trace.