The role of attention in the shift from orientation-dependent to orientation-invariant identification of disoriented objects

In two experiments, the naming of rotated line drawings of natural objects was examined after a training phase in which the objects were either attended or ignored. In the training phase of Experiment 1, subjects were presented with objects in a number of orientations over five repeated blocks of trials. In the center of each object, seven letters (Xs and Ts, colored red or blue) were presented in rapid succession. Half the subjects named aloud the rotated object and ignored the changing letter display (object-attend). The other half ignored the object and counted the number of red Ts, and then used this number to perform a simple multiplication (object-ignore). In the test phase, all subjects named the rotated objects. The results showed that in the first block of trials in the training phase, mean naming time in the object-attend condition increased the further an object was rotated from the upright. This effect of orientation for attended objects was much reduced in the later presentations of the test phase. In contrast, there was no such benefit of prior presentation observed for the naming of objects that had previously been ignored. Instead, a substantial orientation effect was shown for the naming of previously ignored objects, which was similar to the orientation effect observed for attended objects named in the first block. Similar results were found in Experiment 2, in which object-attend subjects in training covertly named the objects and then performed a letter count and multiplication task. In both experiments, performance on the letter count and multiplication task varied with the angle of the ignored object. The results suggest that full attentional resources must be allocated in order for orientation-invariant representations to be formed and used in the identification of rotated objects.     

Another reason why adults find it hard to draw accurately

Misperception of objects is a major cause of inaccuracies in adults' drawing. It has previously been established that participants' drawings are biased by their knowledge of the drawn object. We hypothesised that additional inaccuracy arises because drawings are biased towards participants' idiosyncratic canonical representations of the object. We report that participants' free drawings of a cylinder are correlated with their observational drawings of the same shape, providing evidence that people's observational drawings are distorted by their individual schematic representations of the objects in question. It is unclear whether this reflects a perceptual distortion or a bias in drawing production; in either case, this result provides a further explanation why people are poor at drawing from observation.     

Representation of object orientation in children: Evidence from mirror-image confusions

Although many cognitive functions require information about the orientations of objects, little is known about representation or processing of object orientation. Mirror-image confusion provides a potential clue. This phenomenon is typically characterized as a tendency to confuse images related by left–right reflection (reflection across an extrinsic vertical axis). However, in most previous studies the stimuli were inadequate for identifying a specific mirror-image (or other) relationship as the cause of the observed confusions. Using stimuli constructed to resolve this problem, Gregory and McCloskey (2010) found that adults’ errors were primarily reflections across an object axis, and not left–right reflections. The present study demonstrates that young children's orientation errors include both object–axis reflections and left–right reflections. We argue that children and adults represent object orientation in the same coordinate-system format (McCloskey, 2009), with orientation errors resulting from difficulty encoding or retaining one (adults) or two (children) specific components of the posited representations.     

The impact of meaning and dimensionality on the accuracy of children's copying

Studies of intellectual realism have shown that children aged 7 to 9 copy a line drawing of a cube less accurately than a non‐object pattern composed of the same lines ( Phillips, Hobbs, & Pratt, 1978 ). However, it remains unclear whether performance is worse on the cube because it is a three‐dimensional representation, or because it is a meaningful object, or both. The accuracy with which twenty 7‐year‐old and twenty 9‐year‐old children reproduced 16 line drawings of two‐dimensional and three‐dimensional objects and non‐objects was assessed. Older children copied all types of drawing more accurately than younger participants, and children of all ages copied two‐dimensional drawings more accurately than three‐dimensional. Meaningfulness interacted with dimensionality for ratings of drawing accuracy, assisting the copying of two‐dimensional drawings, but having no impact on the copying of three‐dimensional drawings. For an objective measure based on position, length, and orientation of line, meaningfulness interacted with age group, being beneficial for 7‐ but not 9‐year‐olds. Overall, the results imply that, contrary to previous suggestions, meaningfulness can actually be beneficial to copying.     

Orientation-invariant object recognition: evidence from repetition blindness

The question of whether object recognition is orientation-invariant or orientation-dependent was investigated using a repetition blindness (RB) paradigm. In RB, the second occurrence of a repeated stimulus is less likely to be reported, compared to the occurrence of a different stimulus, if it occurs within a short time of the first presentation. This failure is usually interpreted as a difficulty in assigning two separate episodic tokens to the same visual type. Thus, RB can provide useful information about which representations are treated as the same by the visual system. Two experiments tested whether RB occurs for repeated objects that were either in identical orientations, or differed by 30, 60, 90, or 180 degrees . Significant RB was found for all orientation differences, consistent with the existence of orientation-invariant object representations. However, under some circumstances, RB was reduced or even eliminated when the repeated object was rotated by 180 degrees , suggesting easier individuation of the repeated objects in this case. A third experiment confirmed that the upside-down orientation is processed more easily than other rotated orientations. The results indicate that, although object identity can be determined independently of orientation, orientation plays an important role in establishing distinct episodic representations of a repeated object, thus enabling one to report them as separate events.     

Orientation-specific possibility priming for novel three-dimensional objects

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects’ picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0° to 60°. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60°–180° orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60°).     

Orientation-specific possibility priming for novel three-dimensional objects.

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects' picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0 degree to 60 degrees. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60 degrees-180 degrees orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60 degrees).     

Imagining and naming rotated natural objects

The present experiment examined whether subjects can form and store imagined objects in various orientations. Subjects in a training phase named line drawings of natural objects shown at six orientations, named objects shown upright, or imagined upright objects at six orientations. Time to imagine an upright object at another orientation increased the farther the designated orientation was from the upright, with faster image formation times at 180° than at 120°. Similar systematic patterns of effects of orientation on identification time were found for rotated objects. During the test phase, all subjects named the previously experienced objects as well as new objects, at six orientations. The orientation effect for old objects seen previously in a variety of orientations was much reduced relative to the orientation effect for new objects. In contrast, substantial effects of orientation on naming time were observed for old objects for subjects who had previously seen the objects upright only or upright but imagined at different orientations. The results suggest that the attenuation of initially large effects of orientation with practice cannot be due to imagining and forming representations of objects at a number of orientations.     

Object continuity and the transsaccadic representation of form

Transsaccadic object file representations were investigated in three experiments. Subjects moved their eyes from a central fixation cross to a location between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials on which the target identity matched one of the preview objects, its orientation either matched or did not match the previewed orientation. The results of Experiments 1 and 2 revealed that orientation changes disrupt perceptual continuity for objects located near fixation, but not for objects located further from fixation. The results of Experiment 3 confirmed that orientation changes do not disrupt continuity for distant objects, while showing that subjects nevertheless maintain an object-specific representation of the orientation of such objects. Together, the results suggest that object files represent orientation but that whether or not orientation plays a role in the processes that determine continuity depends on the quality of the perceptual representation.     

Orientation-invariant transfer of training in the identification of rotated natural objects

The effects of stimulus orientation on naming were examined in two experiments in which subjects identified line drawings of natural objects following practice with the objects at the same or different orientations. Half the rotated objects were viewed in the orientation that matched the earlier presentations, and half were viewed at an orientation that mismatched the earlier presentations. Systematic effects of orientation on naming time were found during the early presentations. These effects were reduced during later presentations, and the size of this reduction did not depend on the orientation in which the object had been seen originally. The results are consistent with a dual-systems model of object identification in which initially large effects of disorientation are the result of a normalization process such as mental rotation, and in which attenuation of the effects is due to a shift from the normalization system to a feature/part-based     

Effects of stimulus orientation on the identification of common polyoriented objects

Experimental evidence has shown that the time taken to recognize objects is often dependent on stimulus orientation in the image plane. This effect has been taken as evidence that recognition is mediated by orientation-specific stored representations of object shapes. However, the factors that determine the orientation specificity of these representations remain unclear. This issue is examined using a word-picture verification paradigm in which subjects identified line drawings of common mono- and polyoriented objects at different orientations. A detailed analysis of the results showed that, in contrast to mono-oriented objects, the recognition of polyoriented objects is not dependent on stimulus orientation. This interaction provides a further constraint on hypotheses about the factors that determine the apparent orientation specificity of stored shape representations. In particular, they support previous proposals that objects are encoded in stored representations at familiar stimulus orientations.     

Interference effects in the picture-word stroop task

Line drawings of common objects with an embedded three-or four-letter word or scrambled word were presented either to the right or left visual field. Subjects were to name the line drawing of a common object as fast and as accurately as possible. Reaction times and response accuracy were recorded and analyzed. Percent errors were significantly higher when a line drawing with a word was presented in the right visual field than in the left visual field. Sex of subject was not significant. This finding is analogous to results found when the color-word Stroop task is used.     

To see and remember: visually specific information is retained in memory from previously attended objects in natural scenes

What is the nature of the representation formed during the viewing of natural scenes? We tested two competing hypotheses regarding the accumulation of visual information during scene viewing. The first holds that coherent visual representations disintegrate as soon as attention is withdrawn from an object and thus that the visual representation of a scene is exceedingly impoverished. The second holds that visual representations do not necessarily decay upon the withdrawal of attention, but instead can be accumulated in memory from previously attended regions. Target objects in line drawings of natural scenes were changed during a saccadic eye movement away from those objects. Three findings support the second hypothesis. First, changes to the visual form of target objects (token substitution) were successfully detected, as indicated by both explicit and implicit measures, even though the target object was not attended when the change occurred. Second, these detections were often delayed until well after the change. Third, changes to semantically inconsistent target objects were detected better than changes to semantically consistent objects.     

Semantic consistency versus perceptual salience in visual scenes: Findings from change detection

In a one-shot change detection task, we investigated the relationship between semantic properties (high consistency, i.e., diagnosticity, versus inconsistency with regard to gist) and perceptual properties (high versus low salience) of objects in guiding attention in visual scenes and in constructing scene representations. To produce the change an object was added or deleted in either the right or left half of coloured drawings of daily-life events. Diagnostic object deletions were more accurately detected than inconsistent ones, indicating rapid inclusion into early scene representation for the most predictable objects. Detection was faster and more accurate for high salience than for low salience changes. An advantage was found for diagnostic object changes in the high salience condition, although it was limited to additions when considering response speed. For inconsistent objects of high salience, deletions were detected faster than additions. These findings may indicate that objects are primarily selected on a perceptual basis with subsequent and supplementary effect of semantic consistency, in the sense of facilitation due to object diagnosticity or lengthening of processing time due to inconsistency.     

Viewpoint costs occur during consolidation: evidence from the attentional blink

Do the viewpoint costs incurred when naming rotated familiar objects arise during initial identification or during consolidation? To answer this question we employed an attentional blink (AB) task where two target objects appeared amongst a rapid stream of distractor objects. Our assumption was that while both targets and distractors undergo initial identification only targets are consolidated in a form that allows overt report. We presented line drawings of objects with a usual upright canonical orientation, and separately manipulated the orientation of targets and distractors. In two experiments, targets were defined by colour, whereas in a third experiment they were defined by semantic category. Target 1 orientation influenced the AB, with objects rotated by 90 degrees causing a larger second target deficit than upright and upside-down objects. However, distractor orientation did not affect the magnitude of the second target deficit, regardless of whether targets were defined by colour or semantic category. Taken together, these findings suggest that the visual representations involved in the preliminary recognition of familiar objects are viewpoint-invariant and that viewpoint costs are incurred when these objects are consolidated for report.     

Visual mental representations supporting object drawing: How naming a novel object with a novel count noun impacts on young children's object drawing

Object drawing can be supported by a number of cognitive resources, each making available visual information about the object being drawn. These resources include perceptual input, short-term visual memory, and long-term visual memory. Each of these resources has the potential to make available distinct forms of visual representation, including viewpoint-specific and viewpoint-independent representations, object-specific and category representations, and separate representations of object colour. We review neuropsychological and developmental evidence supporting these claims, including evidence that the same drawing can reflect the influence of multiple forms of visual representation. Seven experiments are then reported, investigating object drawing by 4- to 6-year-old children, to confirm the support for drawing provided by different forms of visual representation. Young children are selected for investigation because their drawing is relatively unconstrained by culturally determined norms which, in our culture, dictate that objects should be drawn just as they appear from the vantage point of the drawer. To distinguish the support provided by object and category representations, the experiments exploit the privileged links between count nouns as object labels, and representations of object categories. In addition, pre-established representations, visual or otherwise, are precluded from influencing drawing by asking the children to draw novel objects, and by creating novel count nouns with which to label the objects. The results reveal how viewpoint-specific perceptual representations, object-specific representations of shape and of colour, and category representations of shape can each impact on object drawing, and in some circumstances on the same drawing. It appears that simple drawing tasks have the potential to reveal some of the distinct types of representation able to support visual cognition.     

Asymmetric response time functions during left-/right-facing discriminations of rotated objects: The short and the long of it

When deciding if a rotated object would face to the left or to the right, if imagined at the upright, mental rotation is typically assumed to be carried out through the shortest angular distance to the upright prior to determining the direction of facing. However, the response time functions for left- and right-facing objects are oppositely asymmetric, which is not consistent with the standard explanation. Using Searle and Hamm’s individual differences adaption of Kung and Hamm’s Mixture Model, the current study compares the predicted response time functions derived when assuming that objects are rotated through the shortest route to the upright with the predicted response time functions derived when assuming that objects are rotated in the direction they face. The latter model provides a better fit to the majority of the individual data. This allows us to conclude that, when deciding if rotated objects would face to the left or to the right if imagined at the upright, mental rotation is carried out in the direction that the objects face and not necessarily in the shortest direction to the upright. By comparing results for mobile and immobile object sets we can also conclude that semantic information regarding the mobility of an object does not appear to influence the speed of mental rotation, but it does appear to influence pre-rotation processes and the likelihood of employing a mental rotation strategy.     

Intuition in the context of object perception: intuitive gestalt judgments rest on the unconscious activation of semantic representations

Intuition denotes the ability to judge stimulus properties on the basis of information that is activated in memory, but not consciously retrieved. In three experiments we show that participants discriminated better than chance fragmented line drawings depicting meaningful objects (coherent fragments) from fragments consisting of randomly displaced line segments (incoherent fragments) or from fragments which were rotated by 180 degrees (inverted fragments), even if participants did not consciously recognize the objects. Unrecognized coherent, but not incoherent or inverted fragments produced reliable priming of correct object names in a lexical decision task, indicating that coherent fragments activated an unconscious semantic object representation. Priming effects were larger for coherent fragments judged as coherent compared to coherent fragments judged as incoherent. We conclude that intuitive gestalt judgments for coherent fragments rested on the activation of semantic object representations, which biased participants' intuitive impression of "gestalt-ness" even when the underlying object representations remained unconscious.     

Negative priming by rotated objects

Previous work has found that repeated exposure to ignored rotated objects is insufficient to allow the formation of orientation-invariant representations (Murray, 1995b). In this study, the negative priming paradigm was used to examine whether the identity of ignored rotated objects was encoded. Subjects were briefly presented with a prime followed by a probe display. One of the two overlapping drawings of objects in each display was selected for further processing, and the other was ignored. In one condition, the ignored objects were upright; in another, they were rotated 240°; and in a final condition, subjects repeatedly named the 240° objects prior to experiencing them as ignored objects in the priming task. Naming latency for the attended probe was slower when it was semantically related to the ignored prime in all conditions. The results suggest that unattended rotated objects are processed to a level of representation that is at least categorical.     

The time to name disoriented natural objects

A series of experiments revealed systematic effects of orientation on the time required to identify line drawings of natural objects. Naming time increases as patterns are rotated further from the upright. With practice, however, the effect of orientation is reduced considerably. Furthermore, the reduced orientation effect with practice on a set of objects does not transfer to a new set of objects, suggesting that the acquired ability to reduce the orientation effect is specific to particular patterns. Finally, for departures in orientation from the upright between 0° and 120°, the magnitude of the orientation effect on identification for patterns seen for the first time is equivalent to that found in a mental rotation task using the same patterns (making left/right decisions about rotated patterns). This final result suggests that novel depictions of a known class of objects may be identified by a process of mental rotation.