This research was supported by an NSF Graduate Research Fellowship to Danielle R. Perszyk and a NIH grant to Sandra R. Waxman (R01HD083310).

The following procedures were approved by the Northwestern University Institutional Review Board and informed consent was obtained from the caregivers of all infants. We recruited infants being raised in environments with more than 50% exposure to English11,17. Infants in all experiments first listened to a soundtrack in which we manipulated their exposure to either lemur vocalizations or backward speech; they then participated in an object categorization task. What varied across infants was (a) the kind of signal they heard in the exposure manipulation and the categorization task (either lemur vocalizations or backward speech) and (b) the extent of the exposure phase (either brief exposure in the lab or prolonged exposure at home). For all infants, the categorization task took place in the lab.
1. Materials
<ol>
	<li>How to create the exposure manipulations
	<ol>
		<li>Select 8 distinct samples of lemur vocalizations and 8 distinct samples of backward speech, each 2 to 4 s in duration. Together, the 8 samples should yield 30 s of each acoustic signal. Ensure that the lemur and backward speech segments are matched as closely as possible for duration (e.g., ~3 s in duration) and for mean frequency (e.g., ~300 Hz).
		<ol>
			<li>To obtain lemur vocalizations, search a database of animal vocalizations or contact a researcher who collects animal vocalizations.</li>
			<li>To create backward speech segments, use a laptop and a software program (e.g., Audacity) to (1) record a research assistant speaking ~3 s sentences in infant-directed speech and (2) temporally reverse (in Audacity: Effect &#62; Reverse) each speech segment.</li>
		</ol>
		</li>
		<li>Choose a piece of classical instrumental music that is longer than 4 min. Here, we used the first 4 min of Beethoven&#39;s String Quartet in C Minor, Op 18 No. 4: III. Menuetto.</li>
		<li>Use an audio editing software program (e.g., Audacity) to import the music (in Audacity: File &#62; Import) and select a portion of the piece that is approximately 4 min in duration (highlight and delete the remainder of the piece).
		<ol>
			<li>Create 2 distinct soundtracks by inserting (i.e., copying and pasting) the 8 selected segments of each type (lemur vocalizations or backward speech) into the musical soundtrack.</li>
			<li>To create the &#34;Lemur&#34; soundtrack, open the 8 lemur vocalization sound files in the same software program (e.g., Audacity) and insert them into the file with the music.
			<ol>
				<li>To do so, highlight an entire lemur vocalization, navigate to Edit &#62; Copy, place the cursor in the music file, and navigate to Edit &#62; Paste. Insert the vocalizations at irregular intervals throughout the soundtrack. Do not place them at musical phrase boundaries. Do this twice for each lemur vocalization, inserting them in a pseudorandomized order to ensure that no 2 identical vocalizations occur in a row. Together, this yields a 5 min loop (4 min of music, interspersed with 1 min of lemur vocalizations).</li>
				<li>Repeat this 5 min soundtrack so that the entire soundtrack lasts approximately 10 min. To do so, highlight the entire 5 min section, navigate to Edit &#62; Copy, place the cursor at the end of the 5-min section, and navigate to Edit &#62; Paste.</li>
			</ol>
			</li>
			<li>To create the 10 min &#34;Backward Speech&#34; soundtrack, replace each lemur vocalization in the Lemur soundtrack with a selected segment of backward speech, using the same pseudorandomized order.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>How to create the categorization task
	<ol>
		<li>Visual materials: Create 2 sets of line drawings by hand. In each set, include 9 members of the same object category (here, use 9 distinct drawings of dinosaurs and 9 distinct drawings of fish). Use a different bright color for each drawing within a given category. Scan these drawings onto a computer and save them as image files. Note that the drawings should be unfamiliar objects to infants at the ages tested.</li>
		<li>Acoustic materials: Select one lemur vocalization and one backward speech segment that were not included in either of the exposure manipulations (1.1.3). Match the lemur and backward speech segments as closely as possible for duration (e.g., ~3 s in duration) and for mean frequency (e.g., ~300 Hz).</li>
		<li>Program a task in MATLAB that includes a familiarization phase and a test phase; this task will be projected onto a 5 ft by 5 ft screen in front of the infant.
		<ol>
			<li>Program the familiarization phase such that 8 of the visual exemplars from a single category (e.g., 8 dinosaurs, each a different color) appear sequentially. Each exemplar should appear for 20 s, on either the right or left side of a screen, in alternating fashion. Create 2 distinct versions, pairing each familiarization exemplar with one of the acoustic stimuli below (&#34;Lemur&#34; and &#34;Backward Speech&#34; conditions, respectively). In both conditions, the acoustic stimulus should occur twice on each familiarization trial; once when the visual exemplar appears, and once again 10 s later.
			<ol>
				<li>In the Lemur condition, program each familiarization exemplar to appear simultaneously with a lemur vocalization.</li>
				<li>In the Backward Speech condition, program each familiarization exemplar to appear simultaneously with a backward speech segment.</li>
			</ol>
			</li>
			<li>During the test phase, present the 9th exemplar from the familiar category (e.g., another dinosaur) and an exemplar from the other category (e.g., a fish). These two images should be identical in color and presented simultaneously (one presented on the right and the other on the left side of the screen) in silence for 20 s.</li>
		</ol>
		</li>
		<li>In programming the categorization task, counterbalance (1) which category will be presented during the familiarization phase, (2) the side on which the first familiarization image will appear, and (3) the side on which the novel and familiar test images will appear.</li>
	</ol>
	</li>
</ol>
2. General Procedures
<ol>
	<li>Exposure phase
	<ol>
		<li>Place the infant close to the caregiver or on their lap in a quiet area. Place a laptop or tablet within the infant&#39;s viewing range (from 1 to 4 ft from the infant).</li>
		<li>Use the laptop or tablet to present either the Lemur or the Backward Speech soundtrack.</li>
	</ol>
	</li>
	<li>Categorization task
	<ol>
		<li>In a semi-darkened test room in the lab, seat the caregiver on a chair 4 ft from a 5 ft by 5 ft screen. Connect the laptop with the categorization task programmed in MATLAB to (1) the screen that will display the categorization task and (2) a projector that will project the task onto the screen.</li>
		<li>Seat the infant on the caregiver&#39;s lap, facing forward.</li>
		<li>Instruct the caregiver to avoid influencing the infant&#39;s behavior in any way. More specifically, instruct them to remain quiet and still throughout the duration of the task and to keep their infant centered, using their midline as a guide. Provide caregivers with a pair of blacked-out glasses to ensure that they cannot see the visual materials.</li>
		<li>Turn on the projector.</li>
		<li>Turn on recording equipment to capture the infants&#39; behavior throughout the task.</li>
		<li>Begin the categorization task by pressing &#34;Run&#34; in MATLAB: Present the Lemur condition if the infant was exposed to the Lemur soundtrack and the Backward Speech condition if the infant was exposed to the Backward Speech soundtrack.</li>
	</ol>
	</li>
	<li>Coding (categorization task only)
	<ol>
		<li>Code the onset and offset of each infant&#39;s left and right looks during both the familiarization and test phases.</li>
		<li>Exclude infants who (1) look at fewer than 6 of the familiarization exemplars; (2) look during less than 40% of the familiarization phase. Also exclude infants if there is parental interference, experimental error or technical failure, or if their performance at test is greater than 2 SD from the mean.</li>
	</ol>
	</li>
	<li>Analyses
	<ol>
		<li>For the familiarization phase, calculate the total the amount of time each infant looked at the familiarization objects.</li>
		<li>For the test phase, calculate a preference score for each infant: (total looking time to novel test image)/(total looking time to both test images).</li>
	</ol>
	</li>
</ol>
3. Experiment 1: Brief Exposure to Lemur Vocalizations
<ol>
	<li>Participants
	<ol>
		<li>Recruit 14 infants at 6 to 7 months of age.</li>
	</ol>
	</li>
	<li>Procedure
	<ol>
		<li>Invite the caregiver and infant into a quiet, comfortable room. In our lab, this room is adjacent to the testing room.</li>
		<li>Exposure manipulation: Play the Lemur soundtrack once, with the music visualizer (e.g., iTunes) present on the screen.</li>
		<li>Categorization task: When the soundtrack finishes, guide the caregiver and infant into the testing room. Begin the categorization task (Lemur condition).</li>
	</ol>
	</li>
</ol>
4. Experiment 2: Brief Exposure to Backward Speech
<ol>
	<li>Participants
	<ol>
		<li>Identical to Experiment 1.</li>
	</ol>
	</li>
	<li>Procedure
	<ol>
		<li>Invite the caregiver and infant into a quiet, comfortable room.</li>
		<li>Exposure manipulation: Play the Backward Speech soundtrack once, with the music visualizer present on the screen.</li>
		<li>Categorization task: When the soundtrack finishes, guide the caregiver and infant into the testing room. Begin the categorization task (Backward Speech condition).</li>
	</ol>
	</li>
</ol>
5. Experiment 3: Prolonged Exposure to Lemur Vocalizations
<ol>
	<li>Participants
	<ol>
		<li>Recruit 14 infants at 4.5 months of age.</li>
	</ol>
	</li>
	<li>Procedure
	<ol>
		<li>By phone, invite the caregiver to participate in a 6 week long study. Explain that the study requires them to expose their infant, at home, to a 10 min soundtrack that contains 8 min of music and 2 min of lemur vocalizations (i.e., Lemur soundtrack). Explain that the study lasts for 6 weeks, beginning when the infant is 4.5 months and ending when the infant is 6 months of age.</li>
		<li>Provide caregivers with this precise tapering schedule7,8,18
		<ol>
			<li>Week 1: Play the soundtrack to infant once a day, every day.</li>
			<li>Week 2: Play the soundtrack to infant once every other day.</li>
			<li>Week 3: Play the soundtrack to infant 3 times during the week.</li>
			<li>Weeks 4-6: Play the soundtrack to infant 2 times per week.</li>
		</ol>
		</li>
		<li>To ensure the fidelity of the exposure manipulation throughout the 6 week exposure manipulation, share with caregivers an online interactive document that (a) outlines their role at every step throughout the 6 week period and (b) asks them to record each date and time at which they played the soundtrack to their infant.</li>
		<li>Send weekly reminders by phone or email to keep caregivers engaged and on track.</li>
		<li>During Week 5, schedule a lab visit for the following week (Week 6). Instruct caregivers that infants should listen to the soundtrack 2 to 4 days before their scheduled lab visit; infants should not listen to the soundtrack either on the day of or the day preceding their visit. 
		NOTE: At the lab visit, there is no exposure manipulation: Infants participate only in the categorization task from Experiment 1 (Lemur condition).</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Di Giorgio, E., Leo, I., Pascalis, O., Simion, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+the+face-perception+system+human-specific+at+birth.">Is the face-perception system human-specific at birth.</a> Dev psychol. 48 (4), 1083-1090 (2012).</li><li>Vouloumanos, A., Hauser, M. D., Werker, J. F., Martin, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+tuning+of+human+neonates'+preference+for+speech.">The tuning of human neonates' preference for speech.</a> Child dev. 81 (2), 517-527 (2010).</li><li>Vouloumanos, A., Werker, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuned+to+the+signal:+the+privileged+status+of+speech+for+young+infants.">Tuned to the signal: the privileged status of speech for young infants.</a> Dev sci. 7 (3), 270-276 (2004).</li><li>Lewkowicz, D. J., Ghazanfar, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+emergence+of+multisensory+systems+through+perceptual+narrowing.">The emergence of multisensory systems through perceptual narrowing.</a> Trends cogn sci. 13 (11), 470-478 (2009).</li><li>Fair, J., Flom, R., Jones, J., Martin, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perceptual+Learning:+12-Month-Olds'+Discrimination+of+Monkey+Faces.">Perceptual Learning: 12-Month-Olds' Discrimination of Monkey Faces.</a> Child dev. 83 (6), 1996-2006 (2012).</li><li>Friendly, R. H., Rendall, D., Trainor, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasticity+after+perceptual+narrowing+for+voice+perception:+reinstating+the+ability+to+discriminate+monkeys+by+their+voices+at+12+months+of+age.">Plasticity after perceptual narrowing for voice perception: reinstating the ability to discriminate monkeys by their voices at 12 months of age.</a> Frontiers in psychology. 4, 718 (2013).</li><li>Pascalis, O., Scott, L. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasticity+of+face+processing+in+infancy.">Plasticity of face processing in infancy.</a> Proc Natl Acad Sci USA. 102 (14), 5297-5300 (2005).</li><li>Heron-Delaney, M., Anzures, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perceptual+training+prevents+the+emergence+of+the+other+race+effect+during+infancy.">Perceptual training prevents the emergence of the other race effect during infancy.</a> PloS one. 6 (5), 19858 (2011).</li><li>Brown, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Words and things: An introduction to language. , (1958).</li><li>Fulkerson, A. L., Waxman, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Words+(but+not+tones)+facilitate+object+categorization:+Evidence+from+6-+and+12-month-olds.">Words (but not tones) facilitate object categorization: Evidence from 6- and 12-month-olds.</a> Cognition. 105 (1), 218-228 (2007).</li><li>Ferry, A. L., Hespos, S. J., Waxman, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Categorization+in+3-+and+4-month-old+infants:+An+advantage+of+words+over+tones.">Categorization in 3- and 4-month-old infants: An advantage of words over tones.</a> Child dev. 81 (2), 472-479 (2010).</li><li>Balaban, M. T., Waxman, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Do+words+facilitate+object+categorization+in+9-month-old+infants.">Do words facilitate object categorization in 9-month-old infants.</a> J exp child psychol. 64, 3-26 (1997).</li><li>Mareschal, D., Quinn, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Categorization+in+infancy.">Categorization in infancy.</a> Trends Cogn Sci. 5 (10), 443-450 (2001).</li><li>Aslin, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What's+in+a+look.">What's in a look.</a> Dev sci. 10 (1), 48-53 (2007).</li><li>Colombo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infant+attention+grows+up:+The+emergence+of+a+developmental+cognitive+neuroscience+perspective.">Infant attention grows up: The emergence of a developmental cognitive neuroscience perspective.</a> Curr Dir Psychol Sci. 11 (6), 196-200 (2002).</li><li>Golinkoff, R. M., Hirsh-Pasek, K., Cauley, K. M., Gordon, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+eyes+have+it:+lexical+and+syntactic+comprehension+in+a+new+paradigm.">The eyes have it: lexical and syntactic comprehension in a new paradigm.</a> J child language. 14 (1), 23-45 (1987).</li><li>Ferry, A. L., Hespos, S. J., Waxman, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonhuman+primate+vocalizations+support+categorization+in+very+young+human+infants.">Nonhuman primate vocalizations support categorization in very young human infants.</a> Proc Natl Acad Sci. , 1-5 (2013).</li><li>Scott, L. S., Monesson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+origin+of+biases+in+face+perception.">The origin of biases in face perception.</a> Psychol sci. 20 (6), 676-680 (2009).</li></ol>

The authors have nothing to disclose.

Here we outline a procedure for examining the role of experience in linking sounds and core cognitive processes early in infancy. Our combined experiments document the first evidence that experience plays a central role in guiding infants to specify which signals, from a broad initial set of possibilities, they will harness to core conceptual processes that ultimately provide the foundations of meaning. They also reveal an intricate interface between nature and nurture: Although experience plays little role, if any, in d...

Human infants are born ready to acquire language, a cultural and cognitive tool that defines us as a species and fundamentally shapes our development. Central to our capacity for learning language are two unique features of human development: Our altriciality and our powerful learning strategies. Together, these features unlock a remarkable degree of early plasticity that enables infants to be highly attuned to input from their environments. For example, although infants come into the world with a set of perceptual preferences and discriminatory capacities sufficiently broad to include the faces and voices of human and nonhuman primates, within months they narrow these preferences to exclusively human signals1,2,3. This process of perceptual narrowing is adaptive on two counts: It increases the signal-to-noise ratio of relevant communicative signals &#8212; those that will guide infants to efficiently and accurately navigate their complex social world &#8212; and it paves the way for integrating information across perceptual modalities (e.g., integrating faces and voices)4 &#8212; an essential element for the multimodal nature of human language. Moreover, because of infants&#39; early plasticity, perceptual narrowing can be prevented or reversed with exposure to nonnative signals (e.g., nonnative language, nonhuman faces, foreign musical rhythms)5,6,8. This illustrates that perceptual narrowing is experience-driven.
Yet to master their native language, infants must do more than tune in to the faces and voices of its speakers. The power of human language is inextricably linked to cognition9. Incredibly, even in their first year of life, infants have begun to link language and cognition: Simply listening to human language promotes infants&#39; ability to form object categories, a building block for their cognition10,11,12.
This is not to say that infants can only form object categories if they are listening to language. On the contrary, decades of research reveal that infants in their first months of life can form at least some object categories in the absence of any sounds13. But not all object categories are equally easy for infants to form. The slightly more difficult categories provide a powerful opportunity to uncover what effect, if any, language may have on infant categorization. To do so, researchers identify object categories that are more difficult for infants to discern in the absence of other supporting information (like language) and then ask whether language (and other sounds) offer infants any advantage in categorization.
Using this logic, an early link between language and object categorization was documented in a novelty preference paradigm designed to accommodate very young infants (Figure 1b)11. This paradigm has two phases. During the familiarization phase, all infants view images of a series of distinct objects (e.g., dinosaurs) presented sequentially in conjunction with a sound. During the test phase, all infants view two new images in silence: One is a new member of the now-familiar category (e.g., another dinosaur) and the other is a member of a novel category (e.g., a fish). Infants&#39; looking time at test serves as an index of categorization. If infants form the category during familiarization, then at test they should distinguish the novel from the familiar image. If infants fail to do so, then at test they should perform at chance14,15,16.
The results were striking. At 3, 4, and 6 months, infants listening to language during familiarization &#8212; but not tone sequences &#8212; successfully formed object categories11,17. Surprisingly, language is not the only sound that exerts this cognitive advantage: At 3 and 4 months, listening to vocalizations of nonhuman primates (Madagascar, blue-eyed lemur: Eulemur macaco flavifrons) confers the same cognitive advantage as human vocalizations17. By 6 months of age, however, infants have tuned this initially broad link specifically to human vocalizations; lemur vocalizations no longer exert an advantageous effect on infant categorization17.
But what mechanism underlies infants&#39; increasing precision in linking language and cognition? Here, we consider the contribution of infants&#39; experience. Does infants&#39; rich experience with human language (and their dearth of experience listening to lemur vocalizations) play a role as they narrow the link between initially privileged signals (e.g., human and nonhuman primate vocalizations) and the core cognitive process of object categorization? Certainly, we cannot test this by manipulating infants&#39; exposure to language. But we can manipulate their exposure to lemur vocalizations. We focus on infants at 6 and 7 months of age &#8212; infants who, in the absence of exposure, no longer link lemur vocalizations and object categorization17. In Experiment 1, we ask whether brief exposure to lemur vocalizations permits them to preserve the link between this signal and object categorization. In Experiment 2, we ask whether brief exposure to backward speech &#8212; a signal that consistently fails to support object categorization at any age17 &#8212; also promotes object categorization. In Experiment 3, we put the question of exposure to a more stringent test, examining whether more prolonged exposure to lemur vocalizations permits them to preserve their initially-broad link.

<table border="0" cellpadding="0" cellspacing="0" width="586">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laptop 1</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Use for presenting exposure soundtrack; preferably using iTunes Visualizer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laptop 2</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for programming and presenting categorization task</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Laptop 3 (optional)</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for coding infant looking behavior (can also use one of the above laptops)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Coding software</td>
			<td style="width:84px;">SuperCoder</td>
			<td style="width:119px;"></td>
			<td>Use for coding infant looking behavior</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Video recorder</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for recording infants&#39; face (looking behavior during categorization task)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mixer</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for integrating information from the video recorder (infant looking behavior) and the visual stimuli (categorization task)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DVD player</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for recording the input from the video recorder (infant looking behavior)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Television</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for viewing input from mixer (screen-in-screen; categorization task in corner of screen showing infant looking behavior)&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Projector</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for projecting visual stimuli of categorization task on screen</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Speakers</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for presenting auditory stimuli during categorization task</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Blacked-out sunglasses</td>
			<td style="width:84px;"></td>
			<td style="width:119px;"></td>
			<td>Use for blocking caretaker&#39;s vision during categorization task</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Statistical analysis software</td>
			<td style="width:84px;">R</td>
			<td style="width:119px;"></td>
			<td>Use for analyzing infant looking behavior</td>
		</tr>
	</tbody>
</table>

experience is instrumental in tuning a link between language and cognition: evidence from 6-  to 7- month-old infants' object categorization

At birth, infants not only prefer listening to human vocalizations, but also have begun to link these vocalizations to cognition: For infants as young as three months of age, listening to human language supports object categorization, a core cognitive capacity. This precocious link is initially broad: At 3 and 4 months, vocalizations of both humans and nonhuman primates support categorization. But by 6 months, infants have narrowed the link: Only human vocalizations support object categorization. Here we ask what guides infants as they tune their initially broad link to a more precise one, engaged only by the vocalizations of our species. Across three studies, we use a novel exposure paradigm to examine the effects of experience. We document that merely exposing infants to nonhuman primate vocalizations enables infants to preserve the early-established link between this signal and categorization. In contrast, exposing infants to backward speech &#8212; a signal that fails to support categorization at any age &#8212; offers no such advantage. Our findings reveal the power of early experience as infants specify which signals, from an initially broad set, they will continue to link to cognition.

Using the procedures outlined above (Figure 1), we ran three experiments to test the effects of exposure as infants refine the links between certain sounds and cognition.
Results of Experiment 1 revealed that brief exposure to lemur vocalizations had a striking effect. Seven month-olds exposed to lemur vocalizations reliably preferred the novel test image, M = 0.57, SD = 0.09; t(13) = ...

Watch this Scientific Journal Video about Experience is Instrumental in Tuning a Link Between Language and Cognition: Evidence from 6-  to 7- Month-Old Infants' Object Categorization at JoVE.com

Experience is Instrumental in Tuning a Link Between Language and Cognition: Evidence from 6-  to 7- Month-Old Infants' Object Categorization

At 3-4 months, listening to human and nonhuman primate vocalizations boosts infants&#39; cognition; by 6 months, only human vocalizations exert this cognitive advantage. We describe an exposure manipulation that reveals the powerful shaping role of experience as infants specify which sounds to link to cognition and which to tune out.

At birth, infants not only prefer listening to human vocalizations, but also have begun to link these vocalizations to cognition: For infants as young as ...

experience-is-instrumental-tuning-link-between-language-cognition

Universidad de Cartagena UDEC

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Introduction to Psychology

Behavior

Unit 1

Thinking, Language And Intelligence

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6.6K Views.  Northwestern University. At 3-4 months, listening to human and nonhuman primate vocalizations boosts infants' cognition; by 6 months, only human vocalizations exert this cognitive advantage. We describe an exposure manipulation that reveals the powerful shaping role of experience as infants specify which sounds to link to cognition and which to tune out.

Video: Experience is Instrumental in Tuning a Link Between Language and Cognition: Evidence from 6-  to 7- Month-Old Infants' Object Categorization

P50 Sensory Gating in Infants

Attentional deficits are common in a variety of neuropsychiatric disorders including attention deficit-hyperactivity disorder, autism, bipolar mood disorder, and schizophrenia. There has been increasing interest in the neurodevelopmental components of these attentional deficits; neurodevelopmental meaning that while the deficits become clinically prominent in childhood or adulthood, the deficits are the results of problems in brain development that begin in infancy or even prenatally. Despite this interest, there are few methods for assessing attention very early in infancy. This report focuses on one method, infant auditory P50 sensory gating.
Attention has several components. One of the earliest components of attention, termed sensory gating, allows the brain to tune out repetitive, noninformative sensory information. Auditory P50 sensory gating refers to one task designed to measure sensory gating using changes in EEG. When identical auditory stimuli are presented 500 ms apart, the evoked response (change in the EEG associated with the processing of the click) to the second stimulus is generally reduced relative to the response to the first stimulus (i.e. the response is &#34;gated&#34;). When response to the second stimulus is not reduced, this is considered a poor sensory gating, is reflective of impaired cerebral inhibition, and is correlated with attentional deficits.
Because the auditory P50 sensory gating task is passive, it is of potential utility in the study of young infants and may provide a window into the developmental time course of attentional deficits in a variety of neuropsychiatric disorders. The goal of this presentation is to describe the methodology for assessing infant auditory P50 sensory gating, a methodology adapted from those used in studies of adult populations.

Methods to record auditory P50 sensory gating, a physiological marker of cerebral inhibition which reflects early stages of attention, are described.

Attentional deficits are common in a variety of neuropsychiatric disorders including attention deficit-hyperactivity disorder, autism, bipolar mood ...

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Transferring Cognitive Tasks Between Brain Imaging Modalities: Implications for Task Design and Results Interpretation in fMRI Studies

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm (the visual oddball task) with a long history of behavioral and electroencephalography (EEG) experiments to a functional magnetic resonance imaging (fMRI) experiment is considered. The aims of this paper are to briefly describe fMRI and when its use is appropriate in cognitive neuroscience; illustrate how task design can influence the results of an fMRI experiment, particularly when that task is borrowed from another imaging modality; explain the practical aspects of performing an fMRI experiment. It is demonstrated that manipulating the task demands in the visual oddball task results in different patterns of blood oxygen level dependent (BOLD) activation. The nature of the fMRI BOLD measure means that many brain regions are found to be active in a particular task. Determining the functions of these areas of activation is very much dependent on task design and analysis. The complex nature of many fMRI tasks means that the details of the task and its requirements need careful consideration when interpreting data. The data show that this is particularly important in those tasks relying on a motor response as well as cognitive elements and that covert and overt responses should be considered where possible. Furthermore, the data show that transferring an EEG paradigm to an fMRI experiment needs careful consideration and it cannot be assumed that the same paradigm will work equally well across imaging modalities. It is therefore recommended that the design of an fMRI study is pilot tested behaviorally to establish the effects of interest and then pilot tested in the fMRI environment to ensure appropriate design, implementation and analysis for the effects of interest.

Transferring a paradigm with a history of use in EEG experiments to an fMRI experiment is considered. It is demonstrated that manipulating the task demands in the visual oddball task resulted in different patterns of BOLD activation and illustrated how task design is crucial in fMRI experiments.

As cognitive neuroscience methods develop, established experimental tasks are used with emerging brain imaging modalities. Here transferring a paradigm ...

Modulating Cognition Using Transcranial Direct Current Stimulation of the Cerebellum

Numerous studies have emerged recently that demonstrate the possibility of modulating, and in some cases enhancing, cognitive processes by exciting brain regions involved in working memory and attention using transcranial electrical brain stimulation. Some researchers now believe the cerebellum supports cognition, possibly via a remote neuromodulatory effect on the prefrontal cortex. This paper describes a procedure for investigating a role for the cerebellum in cognition using transcranial direct current stimulation (tDCS), and a selection of information-processing tasks of varying task difficulty, which have previously been shown to involve working memory, attention and cerebellar functioning. One task is called the Paced Auditory Serial Addition Task (PASAT) and the other a novel variant of this task called the Paced Auditory Serial Subtraction Task (PASST). A verb generation task and its two controls (noun and verb reading) were also investigated. All five tasks were performed by three separate groups of participants, before and after the modulation of cortico-cerebellar connectivity using anodal, cathodal or sham tDCS over the right cerebellar cortex. The procedure demonstrates how performance (accuracy, verbal response latency and variability) could be selectively improved after cathodal stimulation, but only during tasks that the participants rated as difficult, and not easy. Performance was unchanged by anodal or sham stimulation. These findings demonstrate a role for the cerebellum in cognition, whereby activity in the left prefrontal cortex is likely dis-inhibited by cathodal tDCS over the right cerebellar cortex. Transcranial brain stimulation is growing in popularity in various labs and clinics. However, the after-effects of tDCS are inconsistent between individuals and not always polarity-specific, and may even be task- or load-specific, all of which requires further study. Future efforts might also be guided towards neuro-enhancement in cerebellar patients presenting with cognitive impairment once a better understanding of brain stimulation mechanisms has emerged.

Transcranial direct current stimulation (tDCS) over the cerebellum exerts a remote effect on the prefrontal cortex, which can modulate cognition and performance. This was demonstrated using two information-processing tasks of varying complexity, whereby only cathodal tDCS improved performance when the task was difficult, but not easy.

Numerous studies have emerged recently that demonstrate the possibility of modulating, and in some cases enhancing, cognitive processes by exciting brain ...

The Modified Hole Board - Measuring Behavior, Cognition and Social Interaction in Mice and Rats

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure multiple dimensions of unconditioned behavior in small laboratory mammals (e.g., mice, rats, tree shrews and small primates). This paradigm is a valuable alternative for the use of a behavioral test battery, since a broad behavioral spectrum of an animal&#8217;s behavioral profile can be investigated in one single test.
The apparatus consists of a box, representing the &#8216;protected&#8217; area, separated from a group compartment. A board, on which small cylinders are staggered in three lines, is placed in the center of the box, representing the &#8216;unprotected&#8217; area of the set-up. The cognitive abilities of the animals can be measured by baiting some cylinders on the board and measuring the working and reference memory. Other unconditioned behavior, such as activity-related-, anxiety-related- and social behavior, can be observed using this paradigm. Behavioral flexibility and the ability to habituate to a novel environment can additionally be observed by subjecting the animals to multiple trials in the mHB, revealing insight into the animals&#8217; adaptive capacities.
Due to testing order effects in a behavioral test battery, na&#239;ve animals should be used for each individual experiment. By testing multiple behavioral dimensions in a single paradigm and thereby circumventing this issue, the number of experimental animals used is reduced. Furthermore, by avoiding social isolation during testing and without the need to food deprive the animals, the mHB represents a behavioral test system, inducing if any, very low amount of stress.

This protocol describes the modified hole board, which is a behavioral test set-up that comprises the characteristics of an open field and a traditional hole board. This set-up enables the differential analysis of unconditioned behavior of small laboratory mammals as well as the analysis of cognitive abilities.

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure ...

A Mouse Model of Subchronic and Mild Social Defeat Stress for Understanding Stress-induced Behavioral and Physiological Deficits

Stressful life events often increase the incidence of depression in humans. To study the mechanisms of depression, the development of animal models of depression is essential. Because there are several types of depression, various animal models are needed for a deeper understanding of the disorder. Previously, a mouse model of subchronic and mild social defeat stress (sCSDS) using a modified chronic social defeat stress (CSDS) paradigm was established. In the paradigm, to reduce physical injuries from aggressors, the duration of physical contact between the aggressor and a subordinate was reduced compared to in the original CSDS paradigm. sCSDS mice showed increased body weight gain, food intake, and water intake during the stress period, and their social behaviors were suppressed after the stress period. In terms of the face validity of the stress-induced overeating and overdrinking following the increased body weight gain, the sCSDS mice may show some features related to atypical depression in humans. Thus, a mouse model of sCSDS may be useful for studying the pathogenic mechanisms underlying depression. This protocol will help establish the sCSDS mouse model, especially for studying the mechanisms underlying stress-induced weight gain and polydipsia- and hyperphagia-like symptoms.

Here, methods for developing a mouse model of subchronic and mild social defeat stress are described and used to investigate the pathogenic features of depression including hyperphagia- and polydipsia-like symptoms following increased body weight.

Stressful life events often increase the incidence of depression in humans. To study the mechanisms of depression, the development of animal models of ...

The (Spatial) Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different versions of the paradigm, spatial language use and memory for object location are tested under different, experimentally manipulated conditions. This allows us to tease apart proposed models explaining the influence of object knowledge on spatial language (e.g., spatial demonstratives), and spatial memory, as well as understanding the parameters that affect demonstrative choice and spatial memory more broadly. Key to the development of the method was the need to collect data on language use (e.g., spatial demonstratives: &#34;this/that&#34;) and spatial memory data under strictly controlled conditions, while retaining a degree of ecological validity. The language version (section 3.1) of the memory game tests how conditions affect language use. Participants refer verbally to objects placed at different locations (e.g., using spatial demonstratives: &#34;this/that red circle&#34;). Different parameters can be experimentally manipulated: the distance from the participant, the position of a conspecific, and for example whether the participant owns, knows, or sees the object while referring to it. The same parameters can be manipulated in the memory version of the memory game (section 3.2). This version tests the effects of the different conditions on object-location memory. Following object placement, participants get 10 seconds to memorize the object&#39;s location. After the object and location cues are removed, participants verbally direct the experimenter to move a stick to indicate where the object was. The difference between the memorized and the actual location shows the direction and strength of the memory error, allowing comparisons between the influences of the respective parameters.

The Spatial Memory Game: Testing the Relationship Between Spatial Language, Object Knowledge, and Spatial Cognition

We present a protocol to explore the relationship between spatial language production, spatial memory, and object knowledge. The procedure allows experimental manipulation of, and control over, conditions of object knowledge, language at instruction, and physical location, thus teasing apart cognitive and linguistic models describing interactions between these variables.

The memory game paradigm is a behavioral procedure to explore the relationship between language, spatial memory, and object knowledge. Using two different ...

Using Eye Movements Recorded in the Visual World Paradigm to Explore the Online Processing of Spoken Language

In a typical eye tracking study using the visual world paradigm, participants' eye movements to objects or pictures in the visual workspace are recorded via an eye tracker as the participant produces or comprehends a spoken language describing the concurrent visual world. This paradigm has high versatility, as it can be used in a wide range of populations, including those who cannot read and/or who cannot overtly give their behavioral responses, such as preliterate children, elderly adults, and patients. More importantly, the paradigm is extremely sensitive to fine grained manipulations of the speech signal, and it can be used to study the online processing of most topics in language comprehension at multiple levels, such as the fine grained acoustic phonetic features, the properties of words, and the linguistic structures. The protocol described in this article illustrates how a typical visual world eye tracking study is conducted, with an example showing how the online processing of some semantically complex statements can be explored with the visual world paradigm.

The visual world paradigm monitors participants' eye movements in the visual workspace as they are listening to or speaking a spoken language. This paradigm can be used to investigate the online processing of a wide range of psycholinguistic questions, including semantically complex statements, such as disjunctive statements.

In a typical eye tracking study using the visual world paradigm, participants' eye movements to objects or pictures in the visual workspace are recorded ...

A High-performance Liquid Chromatography Measurement of Kynurenine and Kynurenic Acid: Relating Biochemistry to Cognition and Sleep in Rats

The kynurenine pathway (KP) of tryptophan degradation has been implicated in psychiatric disorders. Specifically, the astrocyte-derived metabolite kynurenic acid (KYNA), an antagonist at both N-methyl-d-aspartate (NMDA) and &#945;7 nicotinic acetylcholine (&#945;7nACh) receptors, has been implicated in cognitive processes in health and disease. As KYNA levels are elevated in the brains of patients with schizophrenia, a malfunction at the glutamatergic and cholinergic receptors is believed to be causally related to cognitive dysfunction, a core domain of the psychopathology of the illness. KYNA may play a pathophysiologically significant role in individuals with schizophrenia. It is possible to elevate endogenous KYNA in the rodent brain by treating animals with the direct bioprecursor kynurenine, and preclinical studies in rats have demonstrated that acute elevations in KYNA may impact their learning and memory processes. The current protocol describes this experimental approach in detail and combines a) a biochemical analysis of blood kynurenine levels and brain KYNA formation (using high-performance liquid chromatography), b) behavioral testing to probe the hippocampal-dependent contextual memory (passive avoidance paradigm), and c) an assessment of sleep-wake behavior [telemetric recordings combining electroencephalogram (EEG) and electromyogram (EMG) signals] in rats. Taken together, a relationship between elevated KYNA, sleep, and cognition is studied, and this protocol describes in detail an experimental approach to understanding function outcomes of kynurenine elevation and KYNA formation in vivo in rats. Results obtained through variations of this protocol will test the hypothesis that the KP and KYNA serve pivotal roles in modulating sleep and cognition in health and disease states.

Alterations in the kynurenine pathway (KP) neuroactive metabolites are implicated in psychiatric illnesses. Investigating the functional outcomes of an altered kynurenine pathway metabolism in vivo in rodents may help elucidate novel therapeutic approaches. The current protocol combines biochemical and behavioral approaches to investigate the impact of an acute kynurenine challenge in rats.

The kynurenine pathway (KP) of tryptophan degradation has been implicated in psychiatric disorders. Specifically, the astrocyte-derived metabolite ...

Decomposing the Variance in Reading Comprehension to Reveal the Unique and Common Effects of Language and Decoding

The Simple View of Reading is a popular model of reading that claims that reading is the product of decoding and language, with each component uniquely predicting reading comprehension. Although researchers have argued whether the sum rather than the product of the components is the better predictor, no researchers have partitioned the variance explained to examine the extent to which the components share variance in predicting reading. To decompose the variance, we subtract the R2 for the language-only model from the full model to obtain the unique R2 for decoding. Second, we subtract the R2 for the decoding-only model from the full model to obtain the unique R2 for language. Third, to obtain the common variance explained by language and decoding, we subtract the sum of the two unique R2 from the R2 for the full model. The method is demonstrated in a regression approach with data from students in grades 1 (n = 372), 6 (n = 309), and 10 (n = 122) using an observed measure of language (receptive vocabulary), decoding (timed word reading), and reading comprehension (standardized test). Results reveal a relatively large amount of variance in reading comprehension explained in grade 1 by the common variance in decoding and language. By grade 10, however, it is the unique effect of language and the common effect of language and decoding that explained the majority of variance in reading comprehension. Results are discussed in the context of an expanded version of the Simple View of Reading that considers unique and shared effects of language and decoding in predicting reading comprehension.

Here we present a protocol for decomposing the variance in reading comprehension into the unique and common effects of language and decoding.

The Simple View of Reading is a popular model of reading that claims that reading is the product of decoding and language, with each component uniquely ...