EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 3 Effects of Motor Involvement on Memory Performance for Pictorial

Recent research indicates that memory for real objects is superior to memory for matched pictures (Snow, Skiba, Coleman, & Berryhill, 2014). Although there are several possible explanations for this memory difference, this study was specifically interested in assessing the role of motor involvement. Since real objects offer affordances for action, they may unconsciously engage the motor system when they are viewed. If the motor involvement explanation is correct, I hypothesized that fully engaging the motor system by having individuals interact with the objects should further enhance memory for objects but not for pictures. The study used a 2 (stimuli: object vs picture) x 2 (task: motor vs non-motor) between-subjects design. Thirty participants were randomly assigned to each of the four conditions. Participants engaged in a simple judgment task which involved making a decision by grasping the stimuli (motor) or writing the decision on paper (non-motor). Following the task, recall and recognition scores were assessed. As hypothesized, recall for objects was further enhanced in the motor condition relative to the non-motor condition, and no such improvements were found across the picture conditions. The results of this study suggest that motor system involvement facilitates enhanced memory for objects. EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 3 Effects of Motor Involvement on Memory Performance for Pictorial and 3D Objects Memory is an essential function that provides the foundation for all cognitive processes. Without memories from the past, future experiences would lack meaning. There are various forms of information stored in human memory. These different types of information are accessed and retrieved to act as a guide for human behaviour. When looking at the different forms of information, it is the unspoken assumption that memories for pictures will be remembered better than our memories for studied words. The well-known phrase “a picture is worth more than a thousand words” suggests that our memories for visual displays are something far from ordinary. When people look at pictures, they observe them as a means to understand the story being conveyed. Children for instance, follow stories by observing pictures in books before they have formed a concrete understanding of language. In a sense, words are limited by knowledge, but pictures are easier to understand because they share a universal meaning. For example, despite language barriers, a person travelling in any airport will be able to locate the appropriate washroom by looking at the image on a sign. Pictures are better than memories for words; however, this is not necessarily true when compared with objects (Snow, Skiba, Coleman, & Berryhill, 2014). A picture can be worth a thousand words but becomes useless if a person cannot remember what happened. In a study conducted by Henkel (2013), participants were taken to an art museum and instructed to observe certain objects for several minutes and quickly photograph others. The results of this study demonstrated a memory advantage for objects. Participants remembered fewer details for photographed objects, whereas they were able to report more details for objects that were observed. Overall, the findings of this study lent support in suggesting that our memory for objects is more superior than our memory for pictures EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 4 In the field of memory research, an extensive body of empirical information exists detailing memory for images or words but less exists regarding memory for real objects. Objects are perceptually richer than pictures, and this visual distinction may lend support in suggesting that they are more memorable. Our behaviours are structured around objects more than they are around words or pictures. Imagine baking a cake. When you are baking a cake, you may not follow the instructions of a recipe sequentially step by step; rather, your performance is facilitated by knowing where objects are found within your kitchen. This is because a lot of our memory performance is influenced by objects (Snow et al., 2014), and one may assume that objects are stored and processed in memory differently than words and pictures (Snow et al., 2014). Snow, Skiba, Coleman, and Berryhill (2014) were the first to compare memory for real objects with pictures. Prior to their study, they assumed that memory for real objects was equivalent to memory for images. Their motivation was to explore the possibility of whether memory for real objects was superior to memory for matched images. In their study, participants were exposed to one of three stimulus conditions: real objects, colour photographs of the objects, or line drawings of the objects (altered from the original photograph). Across all conditions, the same orientation and approximate size of the stimuli were accounted for. Results indicated that memory for real objects was superior to memory for photographs, in terms of both recall and recognition. Snow et al. (2014) proposed three possible explanations as to why memory for objects was better than memory for pictures. One explanation focused on the differences in visual cues. Real objects have the advantage of binocular cues, which provide the observer with a rich sense of depth and form when assessing the geometric structure. In the pictorial conditions, the EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 5 participants did not have this advantage. Instead, participants in this condition were limited to monocular cues such as shading and texture which was insufficient to convey visual structure. Based on their findings, Snow et al. (2014) hypothesized that the difference in visual structure may be a possible factor contributing to the object memory advantage. A second explanation suggested that real objects may be more memorable because they activate the dorsal stream at encoding. Real objects are tangible structures, whereas pictures are abstract representations that are harder to understand (DeLoache, Pierroutsakos, & Uttal, 2003). The dorsal stream is important because it considers the spatial locations of objects and influences our visual processing (Polanen & Davare, 2015). Graspable objects work closely with the dorsal stream network (Handy, Tipper, Borg, Grafton, & Gazzinga, 2006) and the dorsal stream regions have been recognized to be active during episodic memory (Vilberg & Rugg, 2008), working memory (Xu & Chun, 2006), and motor tasks (Chao & Martin, 2000). Snow et al. (2014) theorized that real objects may activate the dorsal stream more strongly at encoding; as a result, this may result in qualitatively different processing from pictures. A final explanation, highly related to the second explanation, focused on the idea of object affordances. Affordances provide important cues about the potential actions that can be used with objects and are important for our conceptual knowledge (Glenberg & Kaschak, 2002). Motor affordances help us to encode relationships for how to use objects and facilitate action (Montesano, & Lopes, 2012). A major distinction between objects and pictures is that objects afford action. For example, a cup can be grasped by the handle or rim, but a picture of a cup offers less possibilities. In exploring Snow et al.’s (2014) plausible explanations, the goal of the present study was to further investigate affordances and whether motor system involvement facilitated enhanced memory for objects EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 6 Research suggests that affordances are important for object recognition. Helbig, Graf, and Kiefer (2006), found that affordances play a major role in perception. In their study, participants were primed for affordances. They were shown how a hand acted upon a blurred object. Participants were not exposed to the object; therefore, they only saw the motion and orientation of the hand. By looking at what the hand was doing, it activated the motor cortex. Thus, when the real object was seen, knowing how to act upon it was quicker because of the initial priming. The researchers suggested that the potential to act on the object was primed because the motor cortex was stimulated, and this facilitated object recognition. Other studies have lent similar support by suggesting that motor areas are responsive when people retrieve information for interactions with objects (Boronat et al., 2005). Collectively, these findings suggest that processing manipulable objects will activate regions in the brain associated with motor processing even when there is no explicit instruction to do so. Affordances are referred to as action plans to be carried out by the motor system (Tucker & Ellis, 1998). For instance, Tucker and Ellis examined whether people automatically form a motor response when an object is presented. In the study, participants were presented with objects that had a clear left or right-hand affordance. For example, a frying pan situated on the left has a left-handle affordance. Their results found that participants responded faster when the affordance of the object was congruent with their hand (e.g., left hand object is congruent with a left-hand grasp). The findings suggested that when motor representations are activated they play an integrative role in encoding our memory for the object. Moreover, it demonstrated that people do not merely construct internal visuals of objects, but they are also processing and preparing to act on the objects. Research suggests that manipulable objects can engage different motor regions without EFFECTS OF MOTOR INVOVLEMENT ON MEMORY 7 explicit instruction. For instance, Chao an Martin (200) found that there was increased activation in the premotor cortex when participants viewed manipulable objects relative to when they viewed non-manipulable objects. In their study, they looked to investigate the relationship with the left premotor cortex for manipulable objects and whether these graspable objects a